Sample Business Contracts


Massachusetts-Westford-Westford Technology Park Lease - Michelson Farm-Westford Technology Park IV LP and NetScout Systems Inc.

Lease Forms

  • Start a state-specific lease for the rental of commercial property. Specify the term and rent due, as well as whether the landlord or tenant is responsible for property taxes, insurance, and maintenance and repairs.
  • When a tenant vacates commercial property before the lease term has expired, it may be able to rent the premises to a third party. The tenant would be the sublessor and the third party would be the sublessee. Besides preparing a sublease, both parties will want to review the provisions for assignment or subletting in the original lease agreement between the landlord and the sublessor.
  • Tenants of residential property should prepare a sublease agreement if they are seeking to sublease a room or the entire apartment or house to a third party. All parties should review the original lease agreement to see if there are any restrictions on subletting or assigning the premises.
  • Triple net leases are a type of commercial leases where the tenant has to pay for property taxes, insurance, utilities, and maintenance, in addition to the monthly rent.
  • When renting an office space, tenants should understand the amount of the rent and duration of the lease. Other important terms include whether the space can be subleased, which parties are responsible for maintenance, and whether any furniture and furnishings will be provided.

                                  LEASE BETWEEN
                      MICHELSON FARM - WESTFORD TECHNOLOGY
                                     PARK IV
                               LIMITED PARTNERSHIP
                                       AND
                             NETSCOUT SYSTEMS, INC.
                                       FOR
                            WESTFORD TECHNOLOGY PARK
                                  BUILDING FOUR


<PAGE>


                                    ARTICLE I
                                  TERMS DEFINED

1.1      SUBJECTS REFERRED TO:

Each reference in this Lease to any of the following terms shall mean:


                                           

Landlord:                                     Michelson Farm - Westford Technology Park IV
                                              Limited Partnership

Managing Agent:                               The Gutierrez Company

Landlord's and Managing                       Michelson Farm - Westford Technology Park IV
Agent's Address:                              Limited Partnership
                                              c/o The Gutierrez Company
                                              One Wall Street
                                              Burlington, Massachusetts 01803

Landlord's Representative:                    John A. Cataldo

Tenant:                                       NetScout Systems, Inc.

Tenant's Address:                             321 Billerica Road
(for Notice and Billing)                      Chelmsford, Massachusetts 01824

Tenant's Representative:                      Charles Tillett

Building:                                     The Building, commonly known as Building Four in The
                                              Michelson Farm - Westford Technology Park,
                                              containing approximately 97,500 rentable square feet
                                              on the lot (the "Lot") shown as Lot 4B on a plan
                                              entitled " Definitive Plan of Land, Westford Technology
                                              Park in Westford, Massachusetts" attached to this Lease
                                              as Exhibit "A-2" and recorded with the Middlesex
                                              County North District Registry of Deeds at Book 192,
                                              Plan 24 (Part 2 of 3)

Tenant's Design Completion Date:              September 1, 1997

Scheduled Term
Commencement Date:                            December 1, 1997

Outside Delivery Date:                        March 1, 1998


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                                      -3-




                                           
Term Expiration Date:                         November 30, 2002

Fixed Rent                                    Year 1: $828,750.00/year; $69,062.50/month ($8.50/sf)
                                              Year 2: $828,750.00/year; $69,062.50/month ($8.50/sf)
                                              Year 3: $926,250.00/year; $77,187.50/month ($9.50/sf)
                                              Year 4: $1,023,750.00/year; $85,312.50/month ($10.50/sf)
                                              Year 5: $1,023,750.00/year, $85,312.50/month ($10.50/sf)

Special Provisions:                           Option to Extend - Article III
                                              Signage - Section 12.2

Permitted Uses:                               Uses: Administration, sales and
                                              other general office purpose,
                                              research and development
                                              (including engineering
                                              laboratories), storage and light
                                              manufacturing (including design,
                                              assembly, reassembly and testing
                                              of electronic products and
                                              components) as long as such uses
                                              are permitted uses with respect to
                                              local zoning bylaws and
                                              ordinances.

Premises:                                     The Building and the areas which are the subject of all appurtenant
                                              rights and easements set forth or referred to in Section 2.1 below.

Broker:                                       Lynch Murphy Walsh & Partners
                                              Whittier Partners


         1.2 EXHIBITS - The Exhibits listed below in this Section are
incorporated in this Lease by reference and are to be construed as part of this
Lease:

                                                          

EXHIBIT A                                                    Plan Showing Premises, Plan Showing the Lot and the
                                                             Park, Plan Showing Common Easements

EXHIBIT B                                                    Rules and Regulations

EXHIBIT C                                                    Office Park Covenants

EXHIBIT D                                                    Deed

EXHIBIT E                                                    Subordination, Non-Disturbance and Attornment Agreement

EXHIBIT F                                                    Complete Plans

EXHIBIT G                                                    Estoppel Certificate


<PAGE>


                                      -4-


                                                          
EXHIBIT H                                                    Form of Work Change Order

EXHIBIT I                                                    Certificate of Substantial Completion


                                   ARTICLE II
                             DESCRIPTION OF PREMISES

                  2.1 DEMISE OF PREMISES: In consideration of the rents and
covenants herein stipulated to be paid and performed and upon the terms and
conditions hereinafter specified, Landlord hereby demises and lets to Tenant,
and Tenant hereby leases from Landlord, for the respective terms hereinafter
described, the Premises as described in Article I hereof, which Premises include
the appurtenances described below and in Section 26.10 hereof. The Premises
shall be leased in "as is" condition and specifically and expressly without any
warranties, representations or guarantees, either express or implied, on behalf
of Landlord to Tenant, except as otherwise expressly set forth herein.

         Tenant shall have, as appurtenant to the Building, the right to use in
common with others entitled thereto, subject to reasonable rules and regulations
of general applicability to tenants and owners of other lots in Michelson
Farm-Westford Technology Park (the "Office Park" or the "Park") from time to
time made by Landlord according to Section 12.8 of this Lease of which Tenant is
given notice: all common areas (the "Common Areas") shown on the Plan of Common
Easements of the Office Park attached as part of Exhibit "A", including, without
limitation, a right to access to the Premises at all times, use of all service
areas, use of all utility lines including those for electricity, gas, water and
sewage disposal, use of all facilities for drainage of surface water runoff,
including storm drainage systems and detention areas, use of all grades,
driveways, sidewalks and footways, lighting systems and traffic flow patterns
and, if any, all parking areas designated as common or visitors parking areas
for use of the entire Office Park, if


<PAGE>


                                       -5-


any, including, without limitation, all rights appurtenant to the Lot and the
Building created in the deed (attached as Exhibit D) to Landlord.

         In addition, the Tenant shall have, as appurtenant to the Premises, (i)
the exclusive right and easement with respect to the Lot to use all improvements
thereon including, without limitation, all parking areas, loading areas, service
areas and the like, (ii) the common right and easement with respect to the Lot
to use all means of access to and from the Building and to the Common Areas,
including, without limitation, all sidewalks, and the driveways, grades, roads
and the like, (iii) the common right and easement with respect to the Lot to use
all utility lines, electricity, water, sewage treatment plant, and (iv) the
common right and easement with respect to the Lot to use all facilities for
drainage of surface water runoff; all of the foregoing rights being subject to
reasonable rules and regulations of general applicability to Tenant, tenants,
and owners of lots in the Office Park from time to time made by Landlord
according to Section 12.8 of this Lease.

                                   ARTICLE III
                                      TERM

         3.1 ORIGINAL TERM - To have and to hold for a period (the "Term")
commencing when the Premises are deemed ready for occupancy as provided in
Section 9.2 or if the tenant improvement work is not to be performed by
Landlord's general contractor pursuant to the provisions of Article IX, Section
9.1, on the Scheduled Term Commencement Date (whichever of said dates is
appropriate being hereafter referred to as the "Commencement Date") and
continuing until the Term Expiration Date, unless sooner terminated as provided
in Section 9.2 or Article XIII or in Article XIX or unless extended as provided
in Section 3.2.

         Landlord shall deliver possession of the Premises on the Commencement
Date in broom 


<PAGE>


                                      -6-


clean condition, free of all tenants and occupants and in accordance with the
terms and provisions of Article IX and Article VII (c) of this Lease.

         3.2 EXTENDED TERM - The Tenant has the option to extend this Lease for
one (1) term of five (5) years ("Extended Term") provided the Tenant shall give
to the Landlord written notice of the exercise of this option no later than the
30th day of November, 2001, and such Extended Term shall be upon the same terms,
covenants and conditions hereof, except that the Fixed Rent for the Extended
Term shall be the then Market Rent (as hereinafter defined in Section 4.3).
Landlord shall, within 15 days of receipt of notice of Tenant's election to
extend the Term of this Lease, provide Tenant with notice of the Market Rent in
accordance with the provisions of Article IV. Landlord and Tenant shall, in
accordance with the provisions of Section 4.3 of this Lease, establish the
Market Rent for the Extended Term.

                                   ARTICLE IV
                                      RENT

         4.1 FIXED RENT - The Fixed Rent for the Premises during the Term shall
be as set forth in Article I of this Lease and shall be payable on the first day
of each calendar month during the Term hereof in equal monthly installments also
as set forth in said Article, except that the rent (including both said Fixed
Rent and additional rent pursuant to Section 5.1 hereof) for any portion of a
calendar month during the Term hereof shall be apportioned for such portions.
Rental payments shall be made to the Landlord's and Landlord's Managing Agent's
Address set forth in Article I of this Lease or at such other address as
Landlord may from time to time designate by written notice to the Tenant. All
other payments required by this Lease to be made by Tenant during the Term
thereof as additional rent shall be paid as set forth elsewhere in this Lease.
The term "Annual Rent" for any period of twelve calendar months shall mean Fixed
Rent


<PAGE>


                                      -7-


plus any additional rent payable under the Lease with respect to such period.
All rent payable by Tenant pursuant to this Lease shall be paid without setoff,
adjustment, deduction or abatement, except as otherwise expressly set forth in
this Lease.

         4.2 PAYMENTS - All payments of Annual Rent shall be made payable to
Managing Agent, or to such other person as Landlord may from time to time
designate by written notice to Tenant. If any installment of Annual Rent is paid
more than seven (7) business days after written notice from Landlord that such
rent has not been paid, it shall bear interest at a rate equal to the prime
commercial rate from time to time established by Fleet Bank, or its successor,
plus 4% per annum from the date such installment was due, which interest shall
be immediately due and payable as further additional rent.

         4.3. MARKET RENT - The Market Rent for the Premises, during the
Extended Term, shall be determined as follows: 

         The Market Rent shall be proposed by Landlord within fifteen (15) days
of receipt of Tenant's notice that it intends to exercise its option to extend
the Term pursuant to Section 3.2 hereof (the "Landlord's Proposed Market Rent").
The Landlord's Proposed Market Rent shall be the Market Rent unless Tenant
notifies Landlord, within fifteen (15) days of Tenant's receipt of Landlord's
Proposed Market Rent, that Landlord's Proposed Market Rent is not satisfactory
to Tenant and that Tenant desires to have appraisers determine the Market Rent
("Tenant's Appraisal Notice"), which notice shall specify the name and address
of the appraiser designated by Tenant.

         1.                Landlord shall within five (5) days after receipt of 
                           Tenant's Appraisal Notice, notify Tenant of the name
                           and address of the appraiser designated by Landlord.
                           Such two appraisers shall, within twenty (20) days
                           after the 


<PAGE>


                                      -8-


                           Landlord's designation of an appraiser, make their
                           determinations of the Market Rent in writing and give
                           notice thereof to each other and to Landlord and
                           Tenant. Such two (2) appraisers shall have twenty
                           (20) days after the receipt of notice of each other's
                           determination to confer with each other and to
                           attempt to reach agreement as to the determination of
                           the Market Rent. If such appraisers shall concur in
                           such determination, they shall give notice thereof to
                           Landlord and Tenant and such concurrence shall be
                           final and binding upon Landlord and Tenant. If such
                           appraisers shall fall to concur as to such
                           determination within said twenty (20) day period,
                           they shall give notice thereof to Landlord and Tenant
                           and shall immediately designate a third appraiser. If
                           the two appraisers shall fail to agree upon the
                           designation of such third appraiser within five (5)
                           days after said twenty (20) day period, then they or
                           either of them shall give notice of such failure to
                           agree to Landlord and Tenant and if Landlord and
                           Tenant fail to agree upon the selection of such third
                           appraiser within five (5) days after the appraiser(s)
                           appointed by the parties give notice as aforesaid,
                           then either party on behalf of both may apply to the
                           American Arbitration Association or any successor
                           thereto, or on his or her failure, refusal or
                           inability to act, to a court of competent
                           jurisdiction, for the designation of such third
                           appraiser.

         2.                All appraisers shall be real estate appraisers or
                           consultants who shall have had at least seven (7)
                           years continuous experience in the business of
                           appraising or leasing real estate in the suburban
                           Boston area.


<PAGE>


                                      -9-


         3.                The third appraiser shall conduct such hearings and
                           investigations as he or she may deem appropriate and
                           shall, within ten (10) days after the date of his or
                           her designation, make an independent determination of
                           the Market Rent.

         4.                If none of the determinations of the appraisers
                           varies from the mean of the determinations of the
                           other appraisers by more than ten (10%) percent, the
                           mean of the determinations of the three (3)
                           appraisers shall be the Market Rent for the Premises.
                           If, on the other hand, the determination of any
                           single appraiser varies from the mean of the
                           determinations of the other two (2) appraisers by
                           more than ten (10%) percent, the mean of the
                           determination of the two (2) appraisers whose
                           determinations are closest shall be the Market Rent.

         5.                The determination of the appraisers, as provided
                           above, shall be conclusive upon the parties and shall
                           have the same force and effect as a judgment made in
                           a court of competent jurisdiction.

         6.                Each party shall pay fees, costs and expenses of the
                           appraiser selected by it and its own counsel fees and
                           one-half (1/2) of all other expenses and fees of any
                           such appraisal.

         Notwithstanding the foregoing Section 4.3, Fixed Rent for the Extended
Term shall not be less than the Fixed Rent for the original Term.

                                    ARTICLE V
                         OPERATING AND MAINTENANCE COSTS
                              AND REAL ESTATE TAXES


<PAGE>


                                      -10-


         5.1. COMMON AREA MAINTENANCE - Tenant shall pay to Landlord as
additional rent an additional payment on the first day of each month occurring
during the Term hereof one-twelfth (1/12) of the amount of "Common Area
Maintenance Costs" (as hereinafter defined) for each twelve month period
beginning on each December 1st occurring within the Term, as reasonably
estimated by Landlord from time to time according to this Section 5.1 (Common
Area Maintenance Costs are currently estimated at $89,000 for the year ending
12/31/97). The "Common Area Maintenance Costs" include the expenses in the
following categories and shall be prorated in accordance with the prorations set
forth within each category:

         1.                Building and Lot Related Expenses, which shall be 
                           allocated 100% to Tenant, shall include maintenance
                           of water tight integrity of the roof walls, windows
                           and skylights of the Building (Landlord and Tenant
                           hereby agreeing that in the event that any item for
                           maintenance of the water tight integrity exceeds
                           $5,000, then Tenant shall have the right to require
                           Landlord to obtain 3 competitive bids from a list of
                           subcontractors mutually agreed upon by Landlord,
                           Tenant and Landlord's manufacturer of the item so
                           being maintained); the annual amortized portion for
                           Landlord's cost of Capital Replacements, as defined
                           in Section 6. 1, for any capital items purchased by
                           Landlord in accordance with Section 6. 1, maintenance
                           and repair of, sewer (i.e. on site sewer system),
                           utility, fire main and fire hydrant facilities, and
                           drainage facilities exclusively serving the Building;
                           maintenance of the Building entrance sign;
                           maintenance, repair and striping, snow removal and
                           sanding of the parking and loading area(s) and
                           driveways on the Lot; fertilization, mowing, and
                           watering of 


<PAGE>


                                      -11-

                           lawns on the Lot and landscaping and care of
                           shrubbery and general grounds upkeep of the Lot;
                           changing of street-lamp lights, walk-way lights, and
                           parking lights, and keeping same in proper working
                           condition, and any other services, repairs, or
                           maintenance performed solely for the benefit of the
                           Building; management and Building supervision fees,
                           and insurance premiums procured by Landlord on
                           Tenant's behalf as specified in Article XV;

         2.                Traffic Related Expenses, which shall be allocated on
                           the basis of the ratio of the number of parking
                           spaces exclusively for Tenant's use under this Lease
                           to the aggregate total number of parking spaces
                           within the Office Park, shall include snow removal
                           and sanding of common drives and parking lots,
                           maintenance and repair of the Office Park entrance
                           signs, maintenance and repair of Office Park
                           lighting, traffic signals, and traffic control
                           personnel required for the Office Park, maintenance
                           and repair of Office Park walks, and Office Park
                           non-exclusive parking and any other traffic or common
                           Office Park roadway or walk-way related expenses;

         3.                Landscaping/Drainage/Other General Office Park 
                           Related Expenses, which shall be allocated on the
                           basis of the ratio of the square footage of the
                           Building to the aggregate square footage of all
                           completed buildings including the Building in the
                           Office Park, as such buildings are completed from
                           time to time, shall consist of the maintenance and
                           repair of sewer, utilities, and drainage facilities,
                           maintenance and repair of detention and fire main and
                           fire hydrant facilities which service the Office Park
                           generally 


<PAGE>


                                      -12-


                           and are not exclusive to any single building within
                           the Office Park; fertilization, mowing, and watering
                           of lawns and landscaping and care of shrubbery and
                           general grounds upkeep of access drives, entrance
                           areas and other such portions of the Office Park the
                           landscaping of which actually and substantially
                           benefits the Premises; and liability insurance costs
                           for the Common Areas of the Office Park;

         4.                Sewer Treatment Plant Expenses, including real estate
                           taxes associated with sewer treatment plant land and
                           buildings, shall consist of the expenses of
                           operating, maintaining and repairing the sewage
                           treatment plant, which expenses shall be allocated on
                           the basis of the ratio of the square footage of the
                           Building to the aggregate square footage of all
                           completed buildings including the Building on all
                           lots in the Park, as such buildings are completed and
                           connected for service from time to time to the sewer
                           treatment plant, and the annual amortized portion for
                           Capital Replacements or improvements to the plant
                           shall be allocated on the ratio of the Building
                           square footage to the aggregate square footage of all
                           completed buildings in the Office Park.

         Notwithstanding any contrary provision of this Lease, if Landlord
incurs any Common Area Maintenance Cost that is properly classifiable as a
capital expenditure according to generally accepted accounting principles and
good building management practices and the regulations and directives of the
Internal Revenue Service, then such Common Area Maintenance Cost shall be
amortized over its useful life according to such principles, practices,
regulations and directives, and only the annual amortized portion shall be
included in Common Area 


<PAGE>


                                      -13-


Maintenance Costs for any twelve month period within the Term.

         Notwithstanding anything to the contrary in this Lease contained,
Tenant shall not be required to pay any Common Area Maintenance Costs
attributable to:

         1.                Repairs which are the responsibility of the Landlord
                           as set forth in Article VI, including, structural
                           repairs, as well as repairs or other work occasioned
                           by fire or other casualty or by the exercise of
                           eminent domain;

         2.                Leasing commissions, attorneys' fees, costs and
                           disbursements and other expenses incurred in
                           connection with negotiations or disputes with other
                           tenants, occupants or prospective tenants or
                           occupants of the Office Park;

         3.                Interest, principal, ground rent, or other payments
                           under any mortgage, ground lease or other financing
                           of the Lot or the Office Park;

         4.                Any advertising or promotional expenditures;

         5.                Services or work provided for other tenants and
                           occupants of the Office Park and not substantially
                           benefiting Tenant on a commensurate basis and any
                           expense for which Landlord is entitled to be
                           reimbursed directly by any such other tenant or
                           tenants;

         6.                Overhead or profit increment paid to subsidiaries or
                           affiliates of Landlord for services on or to the
                           Premises to the extent that the costs of such
                           services exceed competitive costs of such services
                           were they not so rendered by a subsidiary or
                           affiliate.

         7.                Expenses related to salaries, wages, benefits and
                           other expenses of executives, principals,
                           administration staff and other employees of Landlord
                           or Landlord's Management Agent not involved directly
                           in the


<PAGE>


                                      -14-


                           operations of the Building or Office Park;

         8.                Expenses related to leasehold improvements made in
                           connection with the preparation of any portion of the
                           Building or Office Park or occupancy by a new or
                           existing tenant which is not generally beneficial to
                           all tenants of the Building;

         9.                Expenses related to efforts to procure new tenants
                           for other buildings or premises located in the Office
                           Park, including advertising expenses, leasing
                           commissions and attorneys fees;

         10.               Expenses related to Landlord's general overhead not
                           directly related to the management or operations of
                           the Building or Office Park;

         11.               Expenses related to depreciation of the Building;

         12.               Expenses related to Landlord or Landlord's Managing
                           Agents breach or violation of a law, lease or other
                           obligations, including fines, penalties and
                           attorney's fees;

         13.               Expenses related to compensation paid to employees or
                           other persons in connection with commercial
                           concessions operated by Landlord or Landlord's
                           Managing Agent;

         14.               Expenses related to fees for licenses, permits or
                           inspections resulting from the act or negligence of
                           Landlord, Landlord's Management Agent or any other
                           tenant of the Office Park;

         15.               Expenses related to any items with respect to which
                           Landlord receives reimbursement from insurance
                           proceeds or from a third party;


<PAGE>


                                      -15-

         16.               Costs and expenses of construction related to an
                           expansion of the rentable area of the Building or
                           Office Park or the parking areas serving the Building
                           or Office Park;

         17.               Expenses related to costs or charges properly 
                           chargeable or attributable to a particular tenant or
                           tenants,

         18.               Expenses related to any utility or other service used
                           or consumed by other tenants or occupants of the
                           Office Park;

         19.               Expenses related to environmental testing,
                           remediation and compliance, Landlord and Tenant
                           hereby agreeing, that this exclusion is not intended
                           to limit the provisions of Section 16.2 of this
                           Lease;

         20.               Expenses related to compliance by Landlord with laws
                           existing as of the date of this Lease, including
                           without limitation the American with Disabilities Act
                           and the regulations of the standards thereunder,
                           except to the extent that any such non-compliance was
                           created by Tenant's use of the Premises; and

         21.               Management and building supervision fees exceeding 
                           2.5% of annual Fixed Rent.

         Tenant shall be solely responsible for paying all utilities including,
but not limited to electricity, water, consumed in the Building or on the Lot,
and the electrical bill shall be placed in the Tenant's name and billed directly
by the utility to Tenant. If Tenant fails to pay any such bills and such failure
continues after written notice to Tenant and the expiration of the applicable
grace period, Landlord shall have the right to pay such bills, and to recover
such payment from Tenant with any interest and/or penalties chargeable thereon
as additional rent. Written notice to 


<PAGE>


                                      -16-


Tenant and grace period will not be applicable in case of emergency with respect
to potential damage to persons or property.

         Tenant recognizes that Landlord may retain the services of such
independent contractors or affiliates as may be necessary for Landlord to
fulfill its obligations hereunder. Landlord shall provide to Tenant within 120
days of the end of each calendar year an annual accounting, in writing, of
actual Common Area Maintenance Costs for such calendar year, and Landlord shall
maintain complete books and records relating to Common Area Maintenance Costs
sufficient to verify these charges and Tenant, its accountants and agents shall
have access to such books and records at reasonable times with prior written
notice. If the total of Tenant's estimated payments on account of Common Area
Maintenance Costs for such calendar year exceeds the actual Common Area
Maintenance Costs for such year, Landlord shall repay to Tenant such excess
thirty (30) days after the delivery to Tenant of such annual accounting. If the
total of Tenant's estimated payments on account of Common Area Maintenance Costs
for such calendar year falls short of the actual Common Area Maintenance Costs
for such year, Tenant shall pay to Landlord such shortage thirty (30) days after
Tenant's receipt of such accounting.

         Based on reasonable estimates of increases in costs covered by this
Section, Landlord reserves the right to adjust the amount of Tenant's estimated
payments on account of Common Area Maintenance Costs annually at the time of
such accounting effective on the first day of each calendar year during the Term
hereof upon thirty (30) days' prior written notice to Tenant and upon providing
Tenant with documentation supporting such estimates. Any such change shall be
effective retroactively to the first day of the calendar year during which the
adjustment is made. Notwithstanding anything contained herein, Landlord reserves
the right to separately invoice Tenant for Tenant's proportionate share of any
actual Common Area Maintenance Costs which 


<PAGE>


                                      -17-


exceeds the amount for such item in Landlord's then current estimate of Common
Area Maintenance Costs by greater than five percent (5%). Any such change shall
be effective retroactively to the first day of the calendar year during which
the adjustment is made. None of such Common Area Maintenance Costs shall exceed
amounts which are charged for such expenses in the Westford, Massachusetts area
for property of the same general type and size as in the Office Park. Landlord
agrees that all services to be provided as part of Common Area Maintenance Costs
shall be obtained by Landlord at commercially reasonable, competitive market
rates consistent with the operation of comparable office buildings in the
Westford, Massachusetts area.

         5.2 TAX EXPENSE Tenant shall pay directly to the relevant taxing
authority (or to Landlord if required by Landlord's mortgagee) real estate taxes
assessed with respect to any period included in the Term hereof (on a pro rata
basis at the beginning or end of the Term) attributable to the Lot and the
Building and any assessment, levy, penalty, imposition or tax (including any tax
which may replace or be assessed in lieu of any of the foregoing), and any
interest due thereon, assessed with respect to any period included in the Term
by any authority and agency having the direct power to tax against the Lot and
the Building (the "Tax Expense"); provided, however, (i) if the amount of any
real estate taxes or any such assessment, levy, penalty, imposition or tax may
lawfully be paid in installments, Tenant may pay such amount over the maximum
period permitted by law, and only the portion of such amount required to be paid
with respect to any period in the Term shall be included in the Tax Expense for
such period, (ii) if the Term includes a partial fiscal tax year at its
beginning or end, the real estate taxes or any such assessment, levy, penalty,
imposition or tax for such tax years shall be prorated according to the
satisfaction of the total number of days in such tax year that are within the
Term, 


<PAGE>


                                      -18-


and only such prorated portion shall be included in the Tax Expense; and (iii)
Tenant shall have no obligation to pay any assessment, levy, penalty, imposition
or tax arising out of a breach or violation by Landlord or any previous owner or
occupancy of the Lot or the Building of any law or obligation. The term "real
estate taxes" means the real estate taxes, betterment assessments, water and
sewer use rents, rates or charges, and such other governmental charges and
impositions which are or may be charged, levied, assessed, imposed or become due
and payable with respect to the Lot, Building, and other improvements comprising
the Premises. All such payments shall be made no later than ten (10) days prior
to the date when interest or penalty would accrue for non-payment or ten (10)
days after Landlord provides Tenant with the real estate tax bill, whichever is
later. Tenant shall furnish to Landlord copies of such bills and receipts
evidencing payment for Landlord's records. Real Estate Taxes are currently
estimated at $51,000 for fiscal year 1998.

         Tenant shall also pay all personal property taxes for Tenant's personal
property on the Premises or used in connection therewith. To the extent
permitted by law, Tenant shall pay, when due, taxes levied or assessed against
Landlord by reason of this Lease on the rental or any other payment required to
be made hereunder whether said taxes are assessed solely on the rental payment
hereunder or jointly with other rentals collected pursuant to any law or
ordinance now existing or hereafter enacted (other than taxes levied on the net
income of Landlord derived therefrom as part of a state or federal income tax
law applicable to Landlord's income, and any income, franchise, gross receipts,
corporation, capital levy, excess profits, revenue, rent, inheritance,
devolution, gift, estate, payroll or stamp tax by whatsoever authority, imposed
or howsoever designated or any tax upon the sale, transfer and/or assignment of
Landlord's title or estate which at any time may be assessed against or become a
lien upon all or any part of the 


<PAGE>


                                      -19-


Premises or this leasehold). Notwithstanding the foregoing, Tenant shall have no
responsibility for late payment penalty or interest if Tenant's payment was
timely as above provided.

         5.3. TAX ABATEMENT - Tenant shall have the right to contest in good
faith by appropriate proceedings diligently pursued the imposition or amount of
any real estate taxes assessed against the Lot or the Building or such personal
property taxes payable by it hereunder, including the right on behalf of, and in
the name of the Landlord, to seek abatements thereto. The Landlord shall
reasonably cooperate with Tenant, at Tenant's sole expense, in any such contest
or abatement proceedings. In the event that Tenant determines not to contest
such taxes and Landlord desires to file such contest, Landlord shall give
written notice of that fact to Tenant and shall have the sole right as to such
tax bill to contest in good faith by appropriate proceedings diligently pursued
the imposition or amount of any real estate taxes assessed against the Lot or
the Building or such other taxes payable by Tenant hereunder, including the
right to seek abatements thereto. In such event, the Tenant shall reasonably
cooperate with Landlord, at Landlord's sole expense, in any such contest or
abatement proceedings. Any tax abatement or rebate received shall be allocated
to the parties in the same proportion as payment.

         If Landlord shall receive on behalf of the Lot or the Building a rebate
or abatement on any tax paid by Tenant, then after deducting therefrom any costs
reasonably incurred by Landlord in obtaining such rebate or abatement, all of
such net rebate or abatement relating to the Lot or the Building or to personal
property taxes assessed against the Tenant's personal property shall be returned
to Tenant to the extent that such rebate or abatement relates to payment made by
the Tenant and not reimbursed by Landlord. If Tenant shall receive on behalf of
the Lot or the Building a rebate or abatement on any tax paid by Tenant, then
after deducting therefrom any costs reasonably incurred by Tenant in obtaining
such rebate or abatement, all of such net rebate


<PAGE>


                                      -20-


or abatement related to the Lot, the Building or to personal property taxes
assessed against the Tenant's property shall be retained by Tenant, as its sole
property, to the extent such rebate or abatement relates to a payment made by
Tenant and not reimbursed by Landlord. The remaining portion of such net rebate
or abatement shall promptly be returned to Landlord.

                                   ARTICLE VI
                              LANDLORD'S COVENANTS

         6.1 LANDLORD'S COVENANTS DURING THE TERM - Landlord shall be
responsible during the Term, at Landlord's expense and not as a cost allocable
to Tenant under Section 5.1, for the structural integrity of the Building and
damage and destruction due to casualty or eminent domain (except as set forth in
Article XIII or below in this Section 6.1 or in Section 11.1 to the contrary).
Landlord shall perform necessary repairs to maintain the structural integrity of
the Building (except that such repairs shall not be required in the case of
settling or sagging of the above items within standard engineering tolerance
provided that the settling and sagging does not affect the surface or structural
integrity of the Building or render the Building unsafe or unfit for normal use,
or for damage or deterioration resulting from overloading by Tenant breaching
the loading provisions of this Lease, or from misuse or negligence of Tenant).

         Landlord shall also be responsible for (i) all exterior maintenance,
repairs and replacements necessary to keep in good condition and working order
the trees, shrubs, plants, landscaping, parking areas, driveways and walkways on
the Lot, (ii) for such repairs as are required by Article XIII hereof, (iii)
compliance with all laws applicable to the Building, the Lot or Office Park, and
(iv) all Capital Replacements (as hereinafter defined) to the heating,
ventilating, air conditioning, plumbing, electrical, emergency and other
mechanical equipment and systems of the Building (collectively, the "Building's
Systems"), so long as such 


<PAGE>


                                      -21-


replacement was not required due to negligence or excessive use of such capital
items by Tenant. "Capital Replacement" shall mean any replacement, the cost of
which is classifiable as a capital expenditure according to generally accepted
accounting principles or the regulations or directives of the Internal Revenue
Service. Landlord will be commercially reasonable and shall use good building
management standards in making Capital Replacement decisions. All costs and
expenses under this Section 6.1 shall be chargeable to Tenant pursuant to the
provisions of Article V, except as otherwise expressly provided in Section 5.1
or this Section 6.1. All other repairs and maintenance, except as specifically
otherwise provided herein, shall be the responsibility of the Tenant.

         In the event that Tenant gives notice to Landlord of a condition which
Tenant believes requires Landlord's repairs or a condition which, if left
uncorrected, will necessitate Landlord's repair, then, in accordance with the
terms of this Section 6.1, Landlord shall respond promptly to investigate such
condition and, if such repairs are Landlord's obligation hereunder, Landlord
shall commence promptly to repair same and to diligently complete said repair.
Tenant agrees during the Term to provide Landlord notice as soon as reasonably
possible of any condition known to Tenant which might require, or if left
uncorrected will necessitate, Landlord's repair pursuant to this Section 6.1.
Tenant shall have the right to require, at reasonable times and with reasonable
notice, a representative of Landlord to inspect the Building for repairs which
may be the responsibility of Landlord.

         6.2 INTERRUPTIONS - Landlord shall not be liable to Tenant for any
compensation or reduction of rent by reason of inconvenience or annoyance or for
loss of business arising from power losses or shortages to the Building or from
the necessity of Landlord's entering the Premises, subject to Section 12.3, for
any of the purposes in this Lease authorized, or for 


<PAGE>


                                      -22-


repairing the Premises or any portion of the Building or improvements or the Lot
or Park, provided, however, (i) Landlord shall use reasonable efforts to remedy
such losses or shortages as quickly as possible and (ii) Landlord, in making any
such entry, repairs or improvements shall not materially interfere with Tenant's
use and occupancy of the Premises. In case Landlord is prevented or delayed from
making any repairs, alterations or improvements, or furnishing any service or
performing any other covenant or duty to be performed on Landlord's part, by
reason of any cause beyond Landlord's reasonable control, Landlord shall not be
liable to Tenant therefor, nor, except as expressly otherwise provided in
Article XIII hereof, shall Tenant be entitled to any abatement or reduction of
rent by reason thereof, nor shall the same give rise to a claim in Tenant's
favor that such failure constitutes actual or constructive, total or partial,
eviction from the Premises. Landlord agrees to provide Tenant with reasonable
advance notice prior to entering the Premises except in the case of emergency.

         Landlord reserves the right to stop any service or utility system when
necessary by reason of accident or emergency or until necessary repairs have
been completed, provided that (i) the Landlord shall complete repairs as soon as
reasonably possible and (ii) Landlord makes reasonable efforts to end the
stoppage. Except in case of emergency repairs, Landlord will give Tenant
reasonable advance notice of any contemplated stoppage and will use reasonable
efforts to avoid interference with Tenant's use and occupancy of the Premises.

                                  ARTICLE VII
                             LANDLORD'S WARRANTIES

         Landlord warrants and represents and covenants and areas as follows:

         (a) Fee simple title to the Premises is vested in the Landlord.

         (b) Landlord has the power and authority to enter into this Lease and
perform the 


<PAGE>


                                      -23-


obligations of Landlord hereunder. This Lease and all other documents executed
and delivered by Landlord constitute legal, valid, binding and enforceable
obligations of Landlord, and there are no claims or defenses, personal or
otherwise, or offsets whatsoever to the enforceability or validity of the Lease.

         (c) Landlord agrees to put all HVAC, mechanical and electrical
equipment currently in the Building in good operating condition prior to the
date of Tenant's permitted access thereto as set forth in Section 9.2.

                                  ARTICLE VIII
                                 USE OF PREMISES

         Tenant may use the Premises for the Permitted Uses specified in Section
1.1 of this Lease.

                                   ARTICLE IX
                           PREPARATION OF THE PREMISES

         9.1      INITIAL CONSTRUCTION

         Tenant shall, on or before Tenant's Design Completion Date, provide to
Landlord for approval: a complete set of construction drawings and
specifications (collectively, the "Complete Plans"), which shall be prepared at
Tenant's expense by "Tenant's Architect", (hereinafter defined) showing and
listing all improvements Tenant intends to make to the Premises, (collectively,
the "Tenant's Work"). The Complete Plans shall include but shall not be limited
to:

         a.       Built-in Furniture and Equipment Layout Plans
         b.       Dimensioned Partition Plans
         c.       Electrical and Telephone Outlet Plans

<PAGE>
                                      -24-

         d.       Reflected Ceiling Plans
         e.       Door and Hardware Schedules
         f        Room Finish Schedule including wall, carpet, and floor tile 
                  colors
         g.       Electrical and Mechanical Engineering Plans

         Landlord and Tenant shall initial the Complete Plans after the same
have been submitted by Tenant and approved by Landlord. At the time of such
approval by Landlord, Landlord agrees to notify or indicate what items will be
required to be removed by Tenant at the Term Expiration Date, or any extensions
thereto.

         Landlord acknowledges that Tenant has selected Newbury Design
Associates as "Tenant's Architect", which architect is acceptable to Landlord.
         
         Landlord and Tenant acknowledge that the Complete Plans may not be
finalized at the time of Lease execution.

         "Tenant's Finish Work" which includes specification, coordination,
supply and installation of furniture, furnishings, telephones and movable
equipment will be the responsibility of Tenant. All of Tenant's Finish Work, and
later changes or additions shall be coordinated with the Tenant's Work being
performed by Landlord in such a manner as to maintain harmonious labor relations
and not damage the Building or Lot or interfere with Building operations. Except
for the Tenant's Finish Work (which such term includes as aforesaid the
installation of the telephone systems, which must be performed by Tenant's
telephone contractor at Tenant's direction and expense (all telephone equipment,
including the telephone interface, shall be installed within the Premises), all
Tenant's Work shall be performed at Tenant's expense by Landlord or a general
contractor selected by Tenant, if prior written approval is granted from
Landlord, which approval shall not be unreasonably withheld,


<PAGE>


                                      -25-


conditioned, or delayed. In the event Tenant elects to use a contractor other
than Landlord, Tenant shall notify Landlord by September 15, 1997 and (i) Tenant
agrees to pay Landlord on the Commencement Date a fee of one and one half
percent (1.5%) of the cost of the Tenant's Work and (ii) Landlord may require
Tenant's general contractor to use a roofing contractor selected by Landlord if
any work is to be done to the roof. Notwithstanding anything contained in
Section 9.2 of this Lease, in the event Tenant elects to use a general
contractor other than Landlord, the Term shall commence on the Scheduled Term
Commencement Date and Fixed Rent shall commence on such date, regardless of
whether or not the Tenant's Work is completed by that date.


         In the event Tenant elects to use Landlord to perform the Tenant's
Work, Tenant shall pay therefor to Landlord within ten (10) days of receipt of
Landlord's Construction Statement (as defined below) (x) the cost of the
Tenant's Work specified in the Complete Plans listed on the "Landlord's
Construction Statement" (hereinafter defined) as completed, plus a Landlord's
contractor's of six percent (6%) of such cost (collectively, the "Tenant
Improvement Reimbursement" or "TIR") and (y) an additional amount equal to the
cost of any changes from the Complete Plans initiated by Tenant by submission to
Landlord of a Form of Work Change Order as hereinafter provided, less any
holdbacks by Landlord to subcontractors or for any "Punch List Work" (as defined
in Section 9.2), which amount shall be due and payable as construction of the
Tenant's Work progresses, on submission by Landlord to Tenant of a statement (
the "Landlord's Construction Statement") on or about the fifth day of each month
listing the Tenant's Work completed as of the date of the Landlord's
Construction Statement, the construction costs incurred for the preceding month
for such completed Tenant's Work, the aforementioned 6% fee and any costs
related to such changes from Tenant's Work. The


<PAGE>


                                      -26-


Landlord's Construction Statement shall be accompanied by a certificate of
Landlord's contractor that all payments then due to laborers, materialmen, and
subcontractors have been made. Landlord shall be responsible for all payments
due to laborers, materialmen, and subcontractors in connection with Tenant's
Work, such that the Premises shall on the Commencement Date be free of all
materialmen or mechanics liens. In no event shall any of the foregoing costs
remain unpaid as of the Commencement Date.

         A copy of all Landlord's Construction Statements shall be sent to
Tenant's Architect for approval in order to verify that all work listed therein
has been satisfactory completed. Tenant's Architect shall also have the right to
periodically inspect the quality and progress of Tenant's Work.

         If Landlord is selected by Tenant to construct the Tenant's Work, then
Landlord shall provide Tenant with construction cost estimates based on the
Complete Plans, including a breakdown thereof, the name of the subcontractor, if
available, and the work and/or materials provided. Unless otherwise mutually
agreed upon by Landlord and Tenant, in the pricing of the cost of the Tenant's
Work, Landlord agrees to obtain three (3) bids from qualified subcontractors
selected from a master list of subcontractors mutually prepared by Landlord and
Tenant prior to the soliciting of bids for any item of the Tenant's Work, but
only to the extent that the same exceeds ten thousand dollars ($10,000.00).
Giving due consideration to factors such as price, delivery commitments, and to
Landlords' construction experience, Landlord shall have the right to select
which subcontractor shall be awarded the work.

         Landlord will not approve any construction, alterations, or additions
requiring unusual expense to readapt the Premises so that the Premises can be
used for the Permitted Uses under this Lease on lease termination or increasing,
the cost of construction, insurance or taxes on the


<PAGE>


                                      -27-


         Building or of Landlord's services called for by Section 5.1, unless
Tenant first gives assurances acceptable to Landlord that such readaptation will
be made prior to such termination without expense to Landlord and makes
provisions acceptable to Landlord for payment of such increased cost. Landlord
will also disapprove any alterations or additions requested by Tenant which will
delay completion of the Tenant's Work. All changes and additions shall be part
of the Building, except such items as Landlord determines in writing at the time
of approval shall be either removed or left in the Premises or Building on
termination of this Lease. 

         The Tenant may request changes to Tenant's Work by altering, adding to,
or deducting from Tenant's Work as set forth in the Complete Plans, subject to
Landlord's prior written approval, which such approval shall not to be
unreasonably withheld, conditioned or delayed, and in accordance with the form
of Work Change Order attached hereto as Exhibit H. Any Work Change Order which
constitutes a reduction or increase in the overall cost of Tenant's Work shall
be credited against or added to the cost of the Tenant's Work, as the case may
be. 

         9.2 PREPARATION OF PREMISES FOR OCCUPANCY 

         If Landlord is obligated to perform the Tenant's Work pursuant to
Section 9.1 and the Complete Plans, Landlord agrees to use reasonable efforts to
have the Premises ready for occupancy on or before the Scheduled Term
Commencement Date, which shall, however, be extended for a period equal to that
of any delays due to governmental regulations, unusual scarcity of or inability
to, obtain labor or materials, labor difficulties, casualty or other causes
reasonably beyond Landlord's control. The Premises shall be deemed ready for
occupancy on the earlier of: 

         (a)           The date on which Tenant occupies all or any part of the 
                       Premises for the Permitted Uses under the Lease; or



<PAGE>
                                      -28-


         (b)           The date on which the Tenant's Work, as specified on the
                       Complete Plans, are Substantially Completed, as
                       hereinafter defined, as certified by Tenant's Architect
                       and Landlord's architect; and Landlord has delivered to
                       Tenant copies of all permits and approvals required to be
                       obtained from any governmental agency prior to occupancy
                       of the Premises by Tenant, including, without limitation,
                       a certificate of occupancy from the Town of Westford or a
                       temporary certificate of occupancy from the Town of
                       Westford which allows Tenant to use and occupy the
                       Premises for the Permitted Uses (including the
                       elevators), and which temporary certificate of occupancy
                       is not conditional on the performance of any work other
                       than the Punch List Work, as defined below, except that
                       such permit(s) and approval(s) shall not be required as a
                       condition of Substantial Completion (as hereinafter
                       defined) if Landlord is unable to secure the same due
                       solely to Tenant's failure to complete Tenant's Finish
                       Work as specified in Section 9.1 above (which date,
                       subject to additional terms and provisions of this
                       Section 9.2, shall hereinafter be referred to as the date
                       of "Substantial Completion".

         The date of "Substantial Completion" shall mean that (i) Tenant's
Architect and Landlord's architect have certified that the Tenant's Work has
been completed fully except for Punch List Work (as hereinafter defined), (ii)
all such permits and approvals as set forth above in Section 9.2(b) have been
obtained by Landlord and delivered to Tenant and (iii) Tenant can use and occupy
the Premises for the Permitted Uses. "Punch List Work" shall mean those matters
(x) which while incomplete do not materially interfere with Tenant's use and
occupancy of the 

<PAGE>
                                      -29-


Premises for the Permitted Uses and (y) the completion of which will not
unreasonably interfere with Tenant's use and occupancy of the Premises for the
Permitted Uses.

         On the date of Substantial Completion, Landlord and Tenant shall
prepare a punch list signed by the Landlord and Tenant listing the Punch List
Work and an agreed-upon cost therefor. One Hundred and Fifty Percent (150%) of
the cost of completion of the Punch List Work shall be withheld from the last
TIR; and at such time as Landlord shall complete the Punch List Work and
Tenant's Architect and Landlord's architect have approved the completion of the
Punch List Work, Tenant shall deliver or cause to be delivered to Landlord the
amount stated in the punch list for the Punch List Work which has been
completed. If completion of the Punch List Work has not been accomplished within
thirty days after the date of Substantial Completion, Tenant may have the Punch
List Work completed by its contractor(s) and deduct the cost of such work from
the retainage from the last TIR as aforesaid.

         If Landlord is unable to complete construction due to delay in Tenant's
compliance with the provisions of Section 9.1 of this Lease, then the Premises
shall be deemed ready for occupancy no later than the Scheduled Term
Commencement Date.

         Landlord shall permit Tenant access to the Building sixty (60) days
prior to the Scheduled Term Commencement Date for the purpose of completing the
Tenant's Finish Work in the Premises prior to the Term when it can be done
without material interference with Landlord's remaining work or for allowing
Tenant's general contractor to complete the Tenant's Work, as the case may be.
All of such work to be constructed by Tenant, or its contractors, shall be
completed in such manner as to not materially damage the Premises or Lot or
materially interfere with the operation of the Building. In addition, such
access shall be subject to the following conditions: (i) Tenant's contractors,
agents or employees work in a harmonious labor 

<PAGE>
                                      -30-


relationship with Landlord's general contractor, and (ii) reasonable prior
written notice is given to Landlord or its general contractor specifying the
work to be done and Landlord approves Tenant's construction drawings, which
approval shall not be unreasonably withheld, conditioned or delayed. During the
period of any preoccupancy of the Premises by Tenant (or its contractors) prior
to the commencement of the Term, no Fixed Rent or additional rent or other
charges shall accrue or be payable, but otherwise such pre-occupancy shall be
subject to and with the benefit of all the terms, covenants and conditions
contained in this Lease.

         In the event of Tenant's failure to comply with the provisions of
Section 9.1 of this Lease, or to submit information, or to deliver construction
drawings and specifications which meet Landlord's approval, Landlord shall,
exercisable by notice to Tenant, deem the Commencement Date to have occurred on
the Scheduled Term Commencement Date. Notwithstanding the foregoing provisions,
if the Premises are not deemed ready for occupancy, as set forth above in
Section 9.2, on or before the Outside Delivery Date for whatever reason, other
than Tenant's default, Tenant may elect to cancel this Lease at any time after
5:00 PM on the day following the Outside Delivery Date, while the Premises are
not deemed ready for occupancy, as set forth above in Section 9.2, by giving
notice to Landlord of such cancellation which shall be effective when given, it
being understood that said election shall be Tenant's sole remedy at law or in
equity for Landlord's failure to have the Premises ready for occupancy.

         9.3 GENERAL PROVISIONS APPLICABLE TO CONSTRUCTION

         All construction work required or permitted by this Lease, whether
performed by Landlord or by Tenant shall be done in a good and workmanlike
manner and in compliance with all applicable laws and all lawful ordinances,
regulations and orders of governmental authority and insurers of the Building.
If Landlord is selected to perform the Tenant's Work, then 

<PAGE>
                                      -31-


Tenant's Architect may inspect the quality and progress of Tenant's Work at
reasonable times and shall promptly give notice of observed defects. If Tenant's
Work is not performed by Landlord, then Landlord's architect shall have the
right to inspect Tenant's Work at reasonable times and shall promptly give
notice of observed defects pertaining to the structure of the Building.

         9.4 REPRESENTATIVES

         Each party authorizes the other to rely in connection with their
respective rights and obligations under this Article IX upon approval and other
actions on the party's behalf by Landlord's Representative in the case of
Landlord or Tenant's Representative in the case of Tenant or by any person
designated in substitution or addition by notice to the party relying. 

                                   ARTICLE X
                              COMPLIANCE WITH LAW

         10.1 TENANT COMPLIANCE - Tenant shall comply, at Tenant's sole expense,
with all applicable laws, ordinances, regulations and orders of any governmental
authority (collectively "the Laws") if such compliance is necessitated by reason
of Tenant's actual use of the Premises, which use shall in any event be in
conformity with the Permitted Uses as specified in Section 1.1 of this Lease.
Except for Tenant's obligations under the preceding sentence, Landlord shall
comply with all Laws applicable to the Building, the Lot or the Office Park.

         10.2 NOTICE - Tenant shall have the right upon giving notice to
Landlord to contest any obligation imposed upon Tenant pursuant to the
provisions of this Article and provided the enforcement of such requirement or
law is stayed during such contest and such contest will not subject the Landlord
to criminal penalty or jeopardize the title to the Premises or otherwise affect
the Premises in any material adverse way. Landlord and Tenant shall each
cooperate with the 

<PAGE>
                                      -32-


other in any such contest and shall execute any documents reasonably required in
the furtherance of such purpose.


                                   ARTICLE XI
                     ALTERATIONS, ADDITIONS AND IMPROVEMENTS

         11.1 ALTERATIONS - Tenant may, from time to time, at its own cost and
expense and without the consent of Landlord, make non-structural non-roof
alterations, additions or improvements to the interior of the Premises
(collectively herein called "Alterations") whose cost in any one instance is
Thirty Thousand Dollars and 00/100 Dollars ($30,000.00) or less, provided Tenant
first notifies Landlord in writing of any such Alterations. If Tenant desires to
make any non-structural non-roof Alterations costing in excess of Thirty
Thousand Dollars and 00/100 Dollars ($30.000.00) in any one instance or any
other alteration, Tenant must first obtain the consent of Landlord thereto,
which consent shall not be unreasonably withheld, conditioned or delayed. In the
instances where Landlord consent is required above, if Landlord reasonably
concludes that the Alterations involve any construction, alterations or
additions requiring unusual expense to readapt the Premises so that the Premises
can be used for the Permitted Uses as defined in this Lease on the Term
Expiration Date, then Landlord shall require by written notice to Tenant at the
time of approval that such readaptation will be made prior to such Term
Expiration Date without expense to Landlord.

         If Tenant desires to make any structural or roof alterations to the
Premises, Tenant must first obtain the consent of Landlord thereto. If Landlord
consents to alterations affecting such structural components or the roof,
Landlord shall be relieved of further maintenance and repair responsibility for
the structural components affected by such alterations, and Tenant shall assume
such responsibility, with respect to that portion of the structural components
(in its entirety), if 

<PAGE>
                                      -33-


any, to which the consent relates, except that Landlord agrees upon request of
Tenant to have such alterations be performed by Landlord or a contractor hired
by Landlord, at Tenant's expense, in which event Landlord shall not be relieved
of any responsibility it may have to the component to be altered.

         Except as permitted in Section 12.2, if Tenant desires to make any
alterations to the precast panels, or to the exterior of the Building, or Lot,
Tenant must first obtain the prior written consent of Landlord thereto, which
may be withheld in Landlord's sole discretion.

         Any and all such Alterations may be done by any general contractor
chosen by Tenant provided any such general contractor is reputable, bondable by
reputable bonding companies, carries the kind of insurance and in the amounts
set forth in Section 11.5 below. Notwithstanding the foregoing, no such bonding
is required for non-structural, non-roof Alterations.

         11.2 LANDLORD PERFORMANCE OF ALTERATIONS - If Tenant, in its sole
discretion, wishes Landlord to perform the work of making Alterations for
Tenant, other than the Tenant's Work to be completed under Article IX, such work
shall be performed at actual cost, plus a fee of fifteen (15%) percent.

         11.3 TENANT PERFORMANCE OF ALTERATIONS - Tenant in making any
Alterations shall cause all work to be done in a good and workmanlike manner
using materials equal to or better than those used in the construction of the
Tenant's Work and shall comply with or cause compliance with all laws and with
any direction given by any public officer pursuant to law. Tenant shall obtain
or cause to be obtained and maintain in effect, as necessary, all building
permits, licenses, temporary and permanent certificates of occupancy and other
governmental approvals which may be required in connection with the making of
the Alterations. Landlord shall cooperate with 

<PAGE>
                                      -34-


Tenant in the obtaining thereof and shall execute any documents reasonably
required in furtherance of such purpose, provided any such cooperation shall be
without expense and/or liability to Landlord.

         11.4 REMOVAL OF ALTERATIONS - At any time during the Term of this
Lease, or on the Term Expiration Date, Tenant may remove any Alterations made,
unless Landlord has indicated in writing at the time of approval of such
Alterations that such Alterations are required to remain on the Premises. In the
event of a removal of any Alterations by Tenant, Tenant shall, at its sole cost,
repair any damage to the Premises caused by such removal.

         11.5 GENERAL PROVISIONS At least annually if such Alterations have
occurred during the past calendar year, Tenant shall furnish to Landlord
as-built sepias and, if applicable, operating manuals, of the work done by
Tenant during such past year and copies of all permits issued in connection
therewith. For all of Tenant's Alterations, whose cost in any one instance is in
excess of $30,000.00, all of Tenant's construction drawings must be prepared at
Tenant's expense by an architect or engineer approved by the Landlord and
Landlord's engineer, which approval shall not be unreasonably withheld or
delayed. Landlord and Tenant shall initial the construction drawings after the
same have been submitted by Tenant to Landlord and approved by Landlord. All of
Tenant's alterations which cost in any instance is in excess of $30,000.00,
shall be constructed by a reputable general contractor, and Landlord may require
that the electrical, heating ventilation and air conditioning, and sprinkler
subcontractors be approved by Landlord, such approval not to be unreasonably
withheld or delayed.

         Tenant shall have its contractor procure and maintain in effect during
the term of such Alterations, the following insurance coverages with an
insurance company or companies authorized to do business in the Commonwealth of
Massachusetts.

<PAGE>
                                      -35-


         (a) Worker's Compensation and Occupational Disease Insurance in
accordance with the laws of the Commonwealth of Massachusetts, along with a "All
States" and "Voluntary Compensation" coverage endorsement.

         (b) Employees Liability insurance with a limit of $100,000.00 per
person per accident, $100,000.00 per person by disease, and $500,000.00 per
policy by disease.

         (c) Comprehensive General Liability including Personal Injury and
Property Damage in the amount of a combined single limit of $2,000,000.00 each
occurrence. Coverage must include the following:

             (1)      premises - operations;
             (2)      elevators and hoists;
             (3)      independent contractor;
             (4)      contractual liability assumed under this contract.

         (d) Comprehensive Auto Liability including Personal Injury and Property
Damage in the amount of a combined single limit of $500,000.00 each occurrence.
Coverage must include the following: 

             (1) owned vehicles; 
             (2) leased vehicles;
             (3) hired vehicles; 
             (4) non-owned vehicles. 

         (e) Owner and Contractor Protective Liability including Personal Injury
and Property Damage in the amount of a combined single limit of $1,000,000.00
each occurrence.

                              ARTICLE XII TENANT'S
                                   COVENANTS

<PAGE>
                                      -36-


         12.1 MAINTENANCE AND REPAIR - Except as provided in Sections 6.1 with
respect to maintenance, repair and other such obligations of Landlord and 13.1
except with respect to repair and restoration of damage or destruction arising
out of a fire or other casualty or the exercise of eminent domain, and except as
to reasonable wear and tear, Tenant shall: keep the Premises and all fixtures
thereon and therein in good repair, operating condition and working order; make
all structural repairs necessitated by Tenant's misuse or negligence; make and
perform or cause to be made or performed all interior maintenance, repairs, and
replacements necessary to keep the Premises in such condition, including,
without limitation, by their inclusion, interior repainting, and replacement of
glass damaged or broken and of floor and wall coverings worn or damaged; keep
all roof drains clear of blockage by snow and other obstructions or debris;
except for Capital Replacements (except as otherwise set forth in Section 6.1),
keep all plumbing, lighting, elevator, heating, ventilating, air conditioning
and other utility and mechanical systems in the Premises properly maintained and
operating in good operating condition; and except for Capital Replacements
(except as otherwise set forth in Section 6. 1), properly maintain the plumbing,
lighting, elevator, heating, ventilating, air conditioning and other utility and
mechanical systems in accordance with any manufacturers warranty and product
standards with fully licensed contractors and under contracts, each reasonably
acceptable to Landlord, qualified to perform the service. Landlord and its
agents reserve the right to inspect the systems to insure proper maintenance in
accordance with Section 12.3 of this Lease. If Landlord, in Landlord's
reasonable judgment, determines such systems have not been properly and
adequately maintained, as herein required, then Landlord, after written notice
to Tenant and the expiration of the applicable grace period, shall have the
right to remedy such maintenance deficiency and 

<PAGE>
                                      -37-


apportion all reasonable costs of such inspections and maintenance to Tenant's
Common Area Maintenance Costs specified in Article V, Landlord and Tenant hereby
agreeing that written notice or grace period not to be applicable in case of
emergency with respect to persons or property.

         Tenant further covenants to (i) neither commit nor suffer waste and
(ii) at the expiration or termination of this Lease peaceably to yield up the
Premises in such order, repair and condition as Tenant is required to maintain
hereunder, first removing all goods and effects of Tenant which Tenant is
required to remove or which Tenant is permitted to remove and desires to remove
and (iii) to repair all damage caused by such removal leaving the Premises clean
and neat and in a condition as required under the terms of this Lease.

         12.2 SIGNS - Tenant shall not, without the prior written consent of
Landlord, which consent shall not be unreasonably withheld, conditioned or
delayed (but may be withheld in Landlord's sole discretion if Tenant is not
leasing at least sixty-six percent (66%) of the Building), (a) paint, place or
replace any signs on the Lot or the Premises or anywhere on the exterior of the
Building (notwithstanding the provisions of Section 11.1 to the contrary), or
(b) place any curtains, blinds (other than standard vertical blinds), shades,
awnings, or flagpoles, or the like, in the Premises or anywhere on or in the
Building visible from outside the Building. Tenant shall pay the expenses
involved in the erection of any sign and of obtaining permits therefor. Tenant
warrants that it shall obtain (and furnish copies thereof to Landlord) all
necessary permits and approvals in compliance with local codes and ordinances
prior to erecting any such sign (s) and, at Landlord's request, Tenant shall
remove said sign (s) upon the termination of this Lease.

<PAGE>
                                      -38-


         12.3 ENTRY AND INSPECTION - Tenant shall permit Landlord and Landlord's
agents and invitees at reasonable times and upon reasonable advance notice
except in emergency in which case notice may be given by telephone or in person,
during Tenant's regular business hours: to examine the Premises, and, if
Landlord shall so elect, to exercise its rights and perform its obligations
under this Lease; to show the Premises to prospective purchasers, prospective or
actual mortgagees, and prospective or actual institutional investors; and, at
any time within twelve (12) months preceding the expiration of the Term, to show
the Premises to prospective tenants, and to affix to any suitable part of the
exterior of the Building and/or the Premises, but not so as to interfere
unreasonably with any of the signs or the windows of the Tenant, a notice to
letting or selling the Premises, and to keep the same so affixed without
hindrance; provided, however, Landlord shall not unreasonably interfere with
Tenant's use or occupancy of the Premises.

         12.4 MISCELLANEOUS Tenant agrees during the Term and so long as
Tenant's occupancy continues:

         (a) Not to permit its employees and officers to use any parking spaces
other than those described in Exhibit "A" and in Section 2.1 of this Lease, and
to make every reasonable effort to keep its invitees from using any spaces other
than those on the Premises; any governmental charges or surcharges or other
monetary obligations imposed by a governmental agency relative to parking rights
with respect to the Premises shall be considered as a Tax Expense and shall be
payable by Tenant in the manner and to the extent provided under the provisions
of Article V, subject to the Tenant's right to contest the same at Tenant's
expense in good faith and by appropriate proceedings.

<PAGE>
                                      -39-


         (b) Not to injure or deface the Premises, or Lot; and not to permit in
the Premises any public auction, nuisance or the emission from the Premises of
any objectionable noise or odor; nor any use thereof which is contrary to law or
ordinances or liable to invalidate or materially increase the premiums for any
insurance on the Building or its contents or liable to render necessary any
alteration or addition to the Premises, unless Tenant is willing to pay for, at
its sole cost and expense, and conduct such alteration or addition, including
obtaining any and all necessary permits and approvals in connection with such
construction thereof.

         12.5 SAFETY APPLIANCES - Tenant agrees to keep the interior of the
Building equipped with all safety appliances, required by law or ordinance or
any other regulation of any public authority and to procure all licenses and
permits so required because of the Permitted Uses.

         12.6 LOADING - Tenant covenants and agrees not to place a load upon the
Premises exceeding 100 pound load per square foot of floor area above the first
floor of which the Premises are constructed, and 200 pounds live load per square
foot of floor area for at grade slab.

         12.7 LABOR OR MATERIALMEN'S LIENS - Tenant covenants and agrees not to
cause or permit any liens for labor or materials performed or furnished at the
request of Tenant or its agents, employees or contractors to attach to the
Premises, or in the event of any such lien so attached to the Premises, Tenant,
within ten (10) days after receiving notice of such lien, shall discharge or
bond over any such liens which may so attach. Tenant may contest any such lien
in good faith at Tenant's sole expense and by appropriate proceedings so long as
the Landlord's interest in the Premises is not jeopardized.

         12.8 RULES AND REGULATIONS - Tenant agrees to comply with the Rules and
Regulations set forth in Exhibit "B" and all other reasonable Rules and
Regulations of general applicability to 

<PAGE>
                                      -40-


tenants and owners of other lots in the Office Park, hereafter made by Landlord,
of which Tenant has been given advance written notice, for the care and use of
the Premises, the Building, the Common Areas and the Office Park and approaches
as further described in the Office Park Covenants attached hereto as Exhibit
"C". Such Rules and Regulations shall not unreasonably interfere with Tenant's
use or occupancy of the Premises, and to the extent any such Rules and
Regulations conflict with this Lease, this Lease shall control. Landlord shall
enforce all such Rules and Regulations uniformly against all tenants.

         12.9 TENANT'S COVENANTS - Tenant has the power and authority to enter
into this Lease and perform the obligations of Tenant hereunder. This Lease and
all other documents executed and delivered by Tenant constitute legal, valid,
binding and enforceable obligations of Tenant.

                                  ARTICLE XIII
                            CASUALTY AND CONDEMNATION

         13.1 CASUALTY - In case during the Term all or any substantial part
(i.e. requiring greater than twelve (12) months to rebuild, as reasonably
determined by Landlord's architect) of the Building is damaged by fire or any
other casualty ("Substantial Casualty"), then this Lease shall, except as
hereinafter provided, terminate at Landlord or Tenant's election, which may be
made by written notice given to the other party within thirty (30) days after
the casualty, which notice of termination shall specify the effective date of
termination which shall not be more than sixty (60) days after the date of
receipt of notice of such termination. In the event of any such Substantial
Casualty, the Fixed Rent and additional rent shall be abated entirely as of the
date of such casualty. In the event of any fire or casualty to the Building,
unless the Lease is so terminated, Landlord shall with reasonable diligence,
repair, replace and restore the Building into substantially the same condition
as it was prior to the casualty for use and occupation to the 

<PAGE>
                                      -41-


extent of the proceeds of insurance, less adjuster's fees, and other reasonable
expenses of collection plus insurance deductibles to be paid by Tenant as
hereunder provided. However, if such damage is not repaired and the Building
restored to substantially the same condition as it was prior to such damage
within a period of twelve (12) full calendar months from the date of such
damage, Tenant within thirty (30) days from the expiration of such period or
from the expiration of any extension thereof pursuant to the terms hereof may
terminate this Lease by notice to Landlord, specifying, a date not more than
sixty (60) days after the giving of such notice on which the term of this Lease
shall terminate. The period within which the required repairs may be
accomplished shall also be extended by the number of days lost as a result of
unavoidable delays, which term shall be defined to include all delays referred
to as Force Majeure in 26.12. up to a maximum period of sixty (60) days. Tenant
shall, in any fire or other casualty which creates a Landlord repair obligation
in accordance with the terms of this Article, upon receipt of written notice and
supporting back up documentation, pay to Landlord prior to Landlord commencing
construction of such repair the then applicable insurance deductible. In
addition, Tenant shall pay Fixed Rent as required by this Lease for any portion
of the Term not covered by rent insurance as required to be obtained by Landlord
in Section 15. 1.

         If the Premises shall be damaged by fire or other casualty, the Fixed
Rent and other charges payable by Tenant under this Lease shall abate or be
reduced proportionately for the period in which, by reason of such damage, there
is substantial interference with Tenant's use and/or occupancy of the Premises.
Such abatement or reduction shall end, if and when, Landlord shall have restored
the Premises to substantially the same condition in which the Premises were
prior to such damage.

<PAGE>
                                      -42-


         13.2 ADDITIONAL CASUALTY PROVISIONS

         (a) Landlord shall not be required to repair or replace any of Tenant's
business machinery, equipment, cabinet work, furniture, personal property and no
damages, compensation or claim shall be payable by Landlord for inconvenience,
loss of business or annoyance arising from any repair or restoration of any
portion of the Premises, necessitated by a fire or other casualty; provided,
however, Landlord shall use reasonable efforts not to interfere with Tenant's
use and occupancy of the Premises.

         (b) In the event of any termination of this Lease pursuant to this
Article XIII, the Term of this Lease shall expire as of the effective
termination date as fully and completely as if such date were the date herein
originally scheduled as the Term Expiration Date. Tenant shall have access to
the Premises at Tenant's sole risk for a period of thirty (30) days after the
date of termination in order to remove Tenant's personal property except as
prohibited by any applicable Governmental agency or official.

         13.3 CONDEMNATION/EMINENT DOMAIN - In the event that the whole or
substantially all of the Building shall be permanently taken or appropriated by
eminent domain or shall be condemned for any public or quasi-public use, then
(and in any such event) this Lease and the Term hereof shall automatically be
terminated as of the effective date of such taking, appropriation or
condemnation.

         In the event that more than a material part (i.e. greater than 30%) of
the floor area of the Building, or any material part of the means of access (
"material" in the case of access shall mean so as to substantially interfere
with the use of the Building), or any material parking ("material" in the case
of parking shall mean the reduction of parking spaces to less than three
(3)parking spaces per 1,000 square feet of Building), shall be so taken,
appropriated or condemned for a 

<PAGE>
                                      -43-


period in excess of one year, then (and in any such event) this Lease and the
Term hereof may be terminated at the election of Tenant by a notice in writing
to Landlord of its election so to terminate within sixty (60) days following the
effective date of such taking, appropriation or condemnation. With respect to
reductions in parking, Landlord may suspend the effectiveness of such notice by
giving its own notice to Tenant within five (5) days of receipt of Tenant's
notice that Landlord shall either (i) remove the impairment to Tenant's use of
the Building by repairing the Building as soon as practicable, or (ii) provide
substitute parking spaces equal to the number taken within reasonable proximity
to the Premises within a reasonable time period, it being agreed that reasonable
time includes weather-related delays associated with winter and spring site work
and paving.

         In the event of any such termination, this Lease and Term hereof shall
expire as of the date specified in such notice of termination from Tenant, which
date shall not be more than sixty (60) days after the date of such notice, as
fully and completely as if such date were the date herein originally scheduled
as the Term Expiration Date. If this Lease is not terminated as above set forth,
Landlord shall, with reasonable diligence and up to the amount of the award,
restore the remainder of the Premises, and the remainder of the means of access,
as nearly as practicably may be to the same condition as obtained prior to such
taking, appropriation or condemnation in which event (i) a just proportion of
the Fixed Rent and additional rent, according to the nature and extent of the
taking, appropriation or condemnation and the resulting permanent injury to the
Premises and the means of access thereto and parking shall be permanently
abated, and (ii) a just proportion of tile remainder of the Fixed Rent and
additional rent, according to the nature and extent of the taking, appropriation
or condemnation and the resultant injury sustained by the Premises and the means
of access thereto and parking shall be abated until what remains of the 

<PAGE>
                                      -44-


Premises and the means of access thereto and parking, shall have been restored
as fully as may be for permanent use and occupation by Tenant hereunder.

         13.4 RESERVATION OF AWARD - Landlord reserves to itself any and all
rights to receive awards made for damages to the Premises, Building or Lot and
the leasehold hereby created, or any one or more of them accruing by reason of
exercise of eminent domain and Tenant hereby releases and assigns to Landlord
all Tenant's rights to such awards, and covenants to deliver such further
assignments and assurances thereof as Landlord may from time to time request. It
is understood and agreed, however, that Landlord does not reserve to itself, and
Tenant does not assign to Landlord, any damages payable for (i) Tenant's
Property as defined in Section 18.1 of this Lease, or (ii) relocation expenses
recoverable by Tenant from such authority in a separate action.

                                   ARTICLE XIV
                              RIGHTS OF MORTGAGEES

         14.1 PRIORITY OF LEASE - Landlord shall use reasonable efforts to
provide to Tenant a Subordination Non-Disturbance and Attornment Agreement (in
the form attached as Exhibit E) from any present holder (a "Mortgagee") of any
mortgage (a "Mortgage") now affecting the Premises. Landlord shall use
reasonable efforts to obtain from any future Mortgagee and any future lessor
under any ground lease or superior lease affecting the Premises a Subordination,
Non-Disturbance and Attornment Agreement (in the form attached as Exhibit E or
in such other form as may be reasonably acceptable to Tenant). Provided that
Landlord has delivered to Tenant such a Subordination, Non-Disturbance and
Attornment Agreement from each such present or future Mortgagee, this Lease
shall be subject and subordinate to the lien of any Mortgage of the Premises.

<PAGE>
                                      -45-


         14.2 LIMITATION ON MORTGAGEE'S LIABILITY - Upon entry and taking
possession of the Premises for any purpose, the holder of a mortgage shall have
all rights of Landlord and, during the period of such possession or ownership,
the duty to perform all Landlord's obligations hereunder. Except during such
period of possession and from and after Foreclosure (as defined in Exhibit E),
no such holder shall be liable, either as mortgagee or as holder of a collateral
assignment of this Lease, to perform, or be liable in damages for failure to
perform, any of the obligations of Landlord, unless and until such holder shall
enter and take possession of the Mortgaged Premises for the purpose of
foreclosing a mortgage. Upon entry for the purpose of foreclosing a mortgage,
such holder shall be liable to perform all of the obligations of Landlord
accruing after said entry, provided that a discontinuance of any foreclosure
proceeding shall terminate the liability of the holder as Landlord.

         14.3 NO PREPAYMENT OR MODIFICATION, ETC. - No Fixed Rent, additional
rent, or any other charge shall be paid more than thirty (30) days prior to the
due dates thereof, and payments made in violation of this provision shall
(except to the extent that such payments are actually received by a Mortgagee in
possession or in the process of foreclosing its mortgage) be a nullity as
against such Mortgagee, and, Tenant shall be liable to such Mortgagee for the
amount of such advance payments made from and after a default under the
applicable Mortgage. No agreement to make or accept any surrender, termination
or cancellation of this Lease and no agreement to modify so as to reduce the
rent, change the Term, or otherwise materially change the rights of Landlord
under this Lease, or to relieve Tenant of any obligations or liability under
this Lease, shall be binding on a Mortgagee unless consented to in writing by
Landlord's Mortgagee of record, if any, such consent not to be unreasonably
withheld or delayed.

<PAGE>
                                      -46-


         14.4 NO RELEASE OF TERMINATION - No act or failure to act on the part
of Landlord which would entitle Tenant under the terms of this Lease, or by law,
to be relieved of Tenant's obligations hereunder or to terminate this Lease,
shall result in a release or termination of such obligations or a termination of
this Lease unless (i) Tenant shall have first given written notice of Landlord's
act or failure to act to Landlord's mortgagee of record, if any, of which
Landlord has given written notice to Tenant of their name and address,
specifying the act or failure to act on the part of Landlord which could or
would give a basis to Tenant's rights and (ii) such mortgagees, after receipt of
such notice, have failed or refused to correct or cure the condition complained
of within thirty (30) days from receipt of such notice, or if cure cannot be
effected within said thirty (30) day period thereafter due to the nature of the
default, Lender shall have a reasonable time to cure, provided that it commences
cure within said thirty (30) day period of time and diligently carries such cure
to completion; but nothing contained in this Section 14.4 shall be deemed to
impose any obligation on any such mortgagee to correct or cure any such
condition.

         14.5     Intentionally Deleted

                                   ARTICLE XV
                                    INSURANCE

         15.1 INSURANCE - If Landlord is selected by Tenant to Construct the
Tenant's Work, Landlord shall procure and continue in force during the
construction of the Tenant's Work Builders Risk insurance whereby Tenant shall
be named additional insured. In addition, Landlord shall procure and continue in
force during the Term and the Extended Term hereof, at Tenant's expense payable
in the manner set forth in Article V, fire and extended coverage insurance,
including vandalism, sprinkler leakage, and malicious mischief, upon the
Building on 

<PAGE>
                                      -47-


a full replacement basis, agreed value endorsement with agreed values for the
Building. The beginning coverage shall be in the amount as is required by
Landlord and its mortgagee up to the full replacement value. The policies
evidencing such insurance shall provide that loss, if any, payable thereunder
shall be payable to the Landlord and/or the Tenant and/or any mortgagee of the
Premises as their respective interests may appear. A certificate of insurance
evidencing the foregoing shall be delivered to the Tenant prior to the execution
of this Lease, and certificates evidencing the renewal of such insurance shall
be delivered to Tenant, upon Tenant's request, at least thirty (30) days before
the expiration of any such policies and providing that the insurance shall not
be canceled within thirty (30) days prior written notice to Tenant. All such
policies shall be placed with responsible companies authorized to do business in
the State wherein the Premises are located. The coverages required by this
Article may be provided by a single "package" policy.

         Tenant shall be responsible for notifying Landlord of additions,
alterations and improvements completed to the interior of the Premises for which
Tenant intends to insure under this Section 15.1. Notification shall include the
cost and description of such work and the date on which coverage should
commence.

         Landlord shall also procure and continue in force during the Term and
Extended Term hereof, at Tenant's expense payable in the manner set forth in
Article V, rental interruption insurance for twelve (12) months or the maximum
obtainable.

         15.2 TENANT LIABILITY INSURANCE - The Tenant shall maintain Commercial
General Liability Insurance at Tenant's expense, including a standard
contractual liability endorsement, with respect to the Premises throughout the
Term with combined single limit coverage of Two Million Dollars ($2,000,000).
The Tenant shall deliver to the Landlord within thirty (30) days of 

<PAGE>
                                      -48-


Landlord's written request a certificate evidencing the aforesaid coverage
issued by insurance companies authorized to do business in Massachusetts and
providing that the insurance indicated therein shall not be canceled without at
least thirty (30) days prior written notice to Landlord. The Landlord will be
named as an additional named insured on such policy.

         15.3 WAIVER OF SUBROGATION - The Landlord and Tenant hereby waive all
causes and rights of recovery against each other, their agents, officers and
employees for any loss occurring to the real or personal property of Landlord or
Tenant, regardless of cause or origin. Landlord and Tenant agree that any
policies presently existing or obtained on or after the date hereof (including
renewals of present policies) shall include a clause or endorsement (a "Waiver
of Subrogation") to the effect that any such release shall not adversely affect
or impair said policies or prejudice the right of the insured to recover
thereunder and that the insurer expressly waives its rights of subrogation
against Landlord or Tenant as the case may be, with respect to any claims under
any such policies. The parties further agree that if said Waiver of Subrogation
shall become unobtainable or unenforceable or shall void the respective
policies, then the respective insurance policies shall not be invalidated, and
said waiver shall become null and void and of no further force and effect.

                                   ARTICLE XVI
                                 INDEMNIFICATION

         16.1 TENANT'S INDEMNITY The Tenant shall, upon timely receipt of
written notice, indemnify, defend and hold the Landlord harmless from and
against any and all suits, claims, and demands arising out of injury or damage
occurring at the Premises or Lot or Office Park because of the negligence or
willful acts of Tenant, its agents, servants, or employees including any
construction activity undertaken by Tenant pursuant to the terms of this Lease.
In no event is 

<PAGE>
                                      -49-


Tenant obligated to indemnify, defend or save harmless Landlord from any loss,
injury, or damage, or part thereof, not attributable to Tenant's negligence or
willful act or those of its agents, servants, or employees.

         In the event the Landlord is notified of a claim, action or proceeding,
or becomes aware of an occurrence, which may result in indemnification by Tenant
as provided above, the Landlord shall give prompt written notice to Tenant and
provide complete particulars known by the Landlord. The Landlord shall
immediately forward to the Tenant every demand, notice, summons or other process
received by Landlord or its representatives.

         Tenant has the exclusive right and obligation to defend any claim,
action, or proceeding wherein Landlord is entitled to indemnification under the
provisions of this Article, and Tenant may settle any such claim, action, or
proceeding, without Landlord's consent or approval.

         The Landlord will fully cooperate with the Tenant in the defense or
settlement of any claim, action, or proceeding.

         16.2 HAZARDOUS MATERIALs - Tenant shall not (either with or without
negligence) cause or permit its employees, agents, contractors or invitees to
cause the escape, disposal or release of any "Hazardous Substances and
Materials" (as defined below) onto or in the vicinity of the Premises other than
the ordinary disposal or release of customary office and cleaning supplies.
Tenant shall not allow the storage or use of such substances or materials in any
manner not sanctioned by law, nor allow to be brought into the Premises any such
materials or substances except to use in the ordinary course of Tenant's
business, and then, except with respect to customary office and cleaning
supplies, only after written notice is given to Landlord of the identity of such
substances or materials. Without limitation, for purposes of this Lease,
"Hazardous Substances and Materials" shall include biohazardous materials and
those materials 

<PAGE>
                                      -50-


or substances regulated by the Comprehensive Environmental Response,
Compensation and Liability Act of 1980, as amended, 42 U.S.C. Section 9601 et
seq., the Resource Conservation and Recovery Act, as amended, 42 U.S.C. Section
6901 et seq., the Massachusetts Hazardous Waste Management Act, as amended,
M.G.L. c.21C, the Massachusetts Oil and Hazardous Material Release Prevention
and Response Act, as amended, M.G.L. c.21E, any applicable local ordinance or
bylaw, and the regulations adopted under these acts (collectively, the
"Hazardous Waste Laws"). If any lender or governmental agency shall ever require
testing to ascertain whether or not there has been any release of hazardous
substances or materials, then the reasonable costs thereof shall be reimbursed
by Tenant to Landlord upon demand as additional charges if such requirement
applies to the Premises and if on such reasonable basis it is determined Tenant
caused the release. If Tenant receives from any federal, state or local
governmental agency any notice of violation or alleged violation of any
Hazardous Waste Law, or if Tenant is obligated to give any notice under any
Hazardous Waste Law, Tenant agrees to forward to Landlord a copy of any such
notice within three (3) days of Tenant's receipt or transmittal thereof. In
addition, Tenant shall execute affidavits, representations and the like from
time to time at Landlord's reasonable request concerning Tenant's best knowledge
of belief regarding the presence of hazardous substances or materials on the
Premises. In all events, Tenant shall indemnify Landlord in the manner provided
in Section 16.1 of this Lease from any release of hazardous substances or
materials on the Premises occurring while Tenant is in possession, or elsewhere
if caused by Tenant, its agents, employees or contractors. Landlord retains the
right to inspect the Premises at all reasonable times, upon reasonable notice to
Tenant, to ensure compliance with this paragraph. The within covenants shall
survive the expiration or 

<PAGE>
                                      -51-


earlier termination of the Lease Term.

         16.3 LANDLORD'S INDEMNIFICATION FOR HAZARDOUS MATERIALS. Landlord
represents and warrants to Tenant that (i) Landlord has delivered to Tenant
copies of all reports, assessments, tests, notices and other documentation in
Landlord's possession relating to the presence, use, storage, release or
disposal of any biologically or chemically active or other hazardous substances
or materials on, in, under, onto, from or in the vicinity of the Premises, and
(ii) to the best of Landlord's knowledge, no such substances or materials have
been used, stored, released or disposed of on, in, under, onto, from or in the
vicinity of the Premises, except for the use, storage, release or disposal of
customary office and cleaning supplies in customary quantities and in accordance
with all applicable laws. If Landlord receives from any federal, state or local
governmental agency any notice of violation or alleged violation of any
Hazardous Waste Law, or if Landlord is obligated to give any notice under any
Hazardous Waste Law in connection with the Office Park, Landlord agrees to
forward to Tenant a copy of any such notice within three (3) days of Landlord's
receipt or transmittal thereof.

         Landlord shall indemnify, defend and hold harmless Tenant from all
suits, claims, demands, liabilities, damages, costs and expenses arising out to
the use, storage, release or disposal of any such substances or material on, in,
under, onto, from or in the vicinity of the Premises because of the negligence
or willful acts of Landlord, its agents, servants, or employees including any
construction activity undertaken by Landlord pursuant to the terms of this
Lease. In no event is Landlord obligated to defend or hold harmless Tenant from
any loss, injury, or damage, or part thereof, not attributable to Landlord's
negligence or willful act or those of its agents, servants, or employees.

<PAGE>
                                      -52-


         In the event the Tenant is notified of a claim, action or proceeding,
or becomes aware of an occurrence, which may result in indemnification by
Landlord as provided above, the Tenant shall give prompt written notice to
Landlord and provide complete particulars known by the Tenant. The Tenant shall
immediately forward to the Landlord every demand, notice, summons or other
process received by Tenant or its representatives.

         Landlord has the exclusive right and obligation to defend any claim,
action, or proceeding wherein Tenant is entitled to indemnification under the
provisions of this Article, and Landlord may settle any such claim, action, or
proceeding without Tenant's consent or approval.

         The Tenant will fully cooperate with the Landlord in the defense or
settlement of any claim, action or proceeding.

                                  ARTICLE XVII
                            ASSIGNMENT AND SUBLETTING

         17.1 TENANT SUBLET - Landlord hereby grants to Tenant the right to
assign this Lease or to sublet all or any portion of the Premises throughout the
Term, provided Tenant first obtains Landlord's consent to such assignment or
subletting in writing. Landlord's consent shall not be unreasonably withheld,
delayed, or conditioned. Landlord's consent to an assignment or subletting shall
be accompanied by a statement addressed to Tenant and the assignee or subtenant,
upon which statement Tenant and the assignee or subtenant may conclusively rely,
stating that Tenant is not in default under the Lease (or setting forth what
respects Tenant is in default), that this Lease has not been amended or modified
(or setting forth such amendments or modifications), the expiration date of this
Lease, and the date to which rent has been paid to Landlord hereunder. It shall
not be unreasonable for Landlord to withhold its consent or disapprove a
sublease or assignment if the proposed sublessee or assignee conflicts with any

<PAGE>
                                      -53-


exclusionary provision (s) of other leases in the Office Park. As additional
rent, Tenant shall reimburse Landlord promptly for reasonable legal and other
expenses incurred by Landlord in connection with any request by Tenant for
consent to assignment or subletting. No assignment or subletting shall affect
the continuing primary liability of Tenant (which, following assignment, shall
be joint and several with the assignee).

         17.2 CONSENT - If the Tenant requests Landlord's consent to a
subletting of all of the Premises for the then balance of the Term, Landlord
shall have the right to terminate this Lease. Landlord shall exercise this
right, if at all, within thirty (30) days of Tenant's request for consent to the
subletting. If Landlord exercises this right, the Lease shall be terminated on
the effective date of the proposed subletting.

         Notwithstanding the foregoing, Landlord's right to terminate the Lease
will be null and void if Landlord receives written notice by Tenant of its
intent to withdraw its request to sublet on or before the fifth day immediately
following Landlord's notice to Tenant of its intention to terminate.

         17.3 LANDLORD'S RESPONSE - In the event Landlord does not respond to
the written request for such consent or exercise its right of recapture within
thirty (30) days of the date of such request from Tenant, Landlord's consent
shall be deemed given.

         17.4 SUBSIDIARY ASSIGNMENT - Notwithstanding anything to the contrary
herein contained, Tenant may assign or sublet all or any portion(s) of the
Premises at any time to a subsidiary of Tenant, to the entity with which or into
which Tenant may merge, to any entity with which Tenant is affiliated, or to a
successor to all or substantially all the assets of Tenant or a division of
Tenant without the need for Landlord's consent to such assignment or subletting,
so long as Tenant remains primarily liable, and without any right on the part of
Landlord to suspend 

<PAGE>
                                      -54-


this Lease as hereinabove set forth and without any obligation of Tenant to
share Rent Differential as set forth in Section 17.5.

         17.5 SUBLEASE AND ASSIGNMENT RENT DIFFERENTIAL - If Landlord consents
to a sublease or assignment, and said sublease or assignment is for a greater
rent than the Fixed Rent or additional rent due from Tenant to Landlord under
this Lease, Tenant shall pay to Landlord (or to any mortgagee in possession or
successor to Landlord through a Foreclosure) on a monthly basis during the term
of any approved sublease or assignment as additional rent hereunder, in addition
to the Fixed Rent and other payments due under this Lease, an amount equal to 50
% of the difference between all fixed rent and additional rent from the time
actually received by Tenant under the sublease or assignment and the Fixed Rent
and additional rent and other payments due under this Lease, after Tenant has
recouped its out-of-pocket expenses with respect to such sublease or assignment
including without limitation, reasonable real estate brokerage commissions,
reasonable legal fees and the reasonable costs of refurbishment of the Premises
for such sublease or assignment (the "Rent Differential"). In case any Fixed
Rent or additional rent is prepaid to Tenant under the sublease or assignment,
only so much as exceeds the net present value of Tenant's obligations to pay
Fixed Rent and additional rent (reasonably estimated) for the balance of the
Term for the portion of the Premises subject to such sublease or assignment
shall be taken into account in computing the Rent Differential or the amounts
due any foreclosing mortgagee or other successor landlord under the next
succeeding sentence. In the event that a tax exempt entity becomes a mortgagee
in possession or a landlord under this Lease through foreclosure or deed in lieu
of foreclosure by reason of a default under the applicable mortgage or through a
participating mortgage transaction or otherwise, in calculating the amount due
in the immediately preceding sentence, there shall be no credit given to Tenant
for its out-of-pocket 

<PAGE>
                                      -55-


expenses involved in such assignment or subletting. In the event the sublease is
for less than the full Premises hereunder, the above rent adjustment shall be
pro rated on a square foot basis. Anything contained in the foregoing provisions
of this Section to the contrary notwithstanding, neither Tenant nor any other
person having interest in the possession, use, occupancy, or utilization of the
Premises shall enter into any lease, sublease, license, concession, or other
agreement for use, occupancy, or utilization of space in the Premises which
provides for rental or other payment for such use, occupancy, or utilization
based, in whole or in part, on the net income or profits derived by any person
from the Premises leased, used, occupied, or utilized (other than an amount
based on a fixed percentage or percentages of receipts or sales), and any such
purported lease, sublease, license, concession, or other agreement shall be
absolutely void and ineffective as a conveyance of any right or interest in the
possession, use, occupancy, or utilization of any part in the Premises. 

                                 ARTICLE XVIII
                               TENANT'S PROPERTY

         18.1 TENANT'S PERSONAL PROPERTY - Tenant's trade fixtures, equipment
and personal property (collectively called "Tenant's Property") however
installed or located on the Premises shall be and remain the property of the
Tenant and may be removed. Tenant shall repair any damage caused by such removal
or installation. Tenant's Property shall be at the sole risk and hazard of
Tenant, and if the whole or any part thereof shall be destroyed or damaged by
fire, water or otherwise, or by the leakage or bursting of water pipes, steam
pipes or other pipes, by theft or from any other cause, unless caused by the
negligence or intentional misconduct of Landlord, its employees, agents or
contractors. No part of said loss or damage is to be charged to or be borne by
Landlord.

<PAGE>


                                      -56-


         18.2 REMOVAL - Upon the expiration or termination of this Lease, the
Tenant will remove Tenant's Property from the Premises; if within ten (10) days
after such expiration or termination, Tenant shall not have removed same, it
shall be deemed abandoned by Tenant. Tenant shall pay to Landlord upon demand
the costs and expenses thereafter incurred by Landlord in removing and storing
Tenant's Property and repairing any damage caused to the Premises or to the
Building caused by the removal of same.

         18.3 NO LIEN - In no event (including a default under this Lease) shall
Landlord have any lien or other security interest in any of Tenant's Property
located in the Premises or elsewhere and Landlord hereby expressly waives and
releases any such lien or other security interest however created or arising.

                                   ARTICLE XIX
                                TENANT'S DEFAULT

         19.1     EVENTS OF DEFAULT:

         (a) If the Tenant shall default in the payment of rent or other
payments required by this Lease and shall fail to cure said default within seven
(7) business days after receipt of written notice of said default from the
Landlord; or

         (b) If the Tenant shall default in the performance or observance of any
other agreement or condition on its part to be performed or observed, and if the
Tenant shall fail to cure said default within thirty (30) days after receipt of
written notice of said default from the Landlord (or if said default shall
require longer than thirty (30) days to cure and the Tenant fails to commence
curing said default within thirty (30) days after receipt of written notice
thereof and to prosecute the curing of the same to completion with due 
diligence); or

         (c) If the Tenant shall file a voluntary petition in bankruptcy or
shall be adjudicated a 


<PAGE>


                                      -57-


bankrupt or insolvent, or shall file any petition or answer seeking any
arrangement, composition, liquidation or dissolution under any present or future
Federal, State, or other statute, law or regulation relating, to bankruptcy,
insolvency or other relief for debtors, or shall seek or consent to or acquiesce
in the appointment of any trustee, receiver or liquidator of the Tenant or of
all or any substantial part of its properties, or of the Premises, or shall make
any general assignment for the benefit of creditors, or shall admit in writing
its inability to pay its debts generally as they become due; or

         (d) If a court shall enter an order, judgment or decree approving a
petition filed against the Tenant seeking any arrangement, composition,
liquidation, dissolution or similar relief under the present or future Federal,
State or other statute, law or regulation relating to bankruptcy, insolvency or
other relief for debtors, and such order, judgment or decree shall remain
un-vacated or un-stayed for an aggregate of sixty (60) days (whether or not
consecutive) (any of the events or conditions described in (a), (b), (c) or (d)
above being called an "Event of Default" in this Lease), then, if any Event of
Default has occurred, the Landlord at any time thereafter may give written
notice to the Tenant specifying the occurrence giving a rise to such Event of
Default and stating that this Lease and the Term hereby demised shall expire and
terminate on the date specified in such notice which shall be at least ten (10)
days after the giving of such notice, and upon the date specified in such
notice, this Lease and the Term, estate and interest hereby demised shall expire
and terminate by limitation and all rights of the Tenant under this Lease shall
cease. In the event the Lease is terminated on account of an Event of Default of
Tenant under any of the provisions contained in this Article, Tenant shall pay
punctually to Landlord all of the sums which Tenant covenants in this Lease to
pay and Landlord's reasonable costs of performing any obligations of the Tenant
under this Lease that 


<PAGE>


                                      -58-


Tenant fails to perform, in the same manner and to the same extent and at the
same time as if this Lease had not been terminated, including all reasonable and
necessary costs and expenses incurred by or on behalf of Landlord, including
reasonable attorney's fees and expenses of employees, arising out of any Event
of Default by the Tenant under this Lease.

         19.2 REPOSSESSION - At any time after any such expiration or
termination of this Lease, the Landlord, without further notice, may enter upon
and reenter the Premises to repossess itself of the Premises, by summary
proceedings, ejectment or otherwise, and may remove the Tenant and all other
persons and any and all property from the Premises (including without limitation
Tenant's Property) as hereinabove provided.

                                   ARTICLE XX
                                     NOTICES

         20.1 NOTICES GENERALLY - All notices, demands, requests and other
instruments which may or are required to be given by either party to the other
under this Lease shall be given in writing. All notices, demands, requests and
other instruments from the Landlord to the Tenant shall be deemed to have been
given when mailed by United States Registered or Certified Mail, postage
prepaid, return receipt requested, addressed to the Tenant at Tenant's Address
with a copy to Testa, Hurwitz & Thibeault LLP, High Street Tower, 125 High
Street Boston, MA 02110 Attn: Real Estate Department; and all notices, demands,
requests and other instruments from Tenant to the Landlord shall be deemed to
have been given when mailed by United States Registered or Certified Mail,
postage prepaid, return receipt requested, addressed to the Landlord at
Landlord's Address with a copy to Hinckley, Allen & Snyder, One Financial
Center, Boston, Massachusetts 02111 Attn: Paul Hedstrom; except that where any
period of time commences under this Lease with notice, such notice shall be
deemed given, and such period shall be deemed 


<PAGE>


                                      -59-


to commence, when postal records indicate delivery was first attempted or
rendered for delivery if refused.

         20.2     INTENTIONALLY DELETED

                                   ARTICLE XXI
                                 QUIET ENJOYMENT

         Landlord covenants and agrees with Tenant that upon Tenant paying the
rent and additional rent and observing the terms, covenants and conditions on
Tenant's part to be observed and performed, Tenant may peaceably and quietly
enjoy the Premises demised hereby.

                                  ARTICLE XXII
                                  HOLDING OVER

         In the event that Tenant occupies any portion of the Premises beyond
the Term Expiration Date, such holding over shall constitute an agreement by
Tenant to pay 150% of the Fixed Rent and additional rent then applicable for
each month or portion thereof in which Tenant shall retain possession of the
Premises or any part there after termination of this Lease, whether by lapse of
time or otherwise due hereunder. In addition, Tenant agrees to pay all damages
(including consequential damages) sustained by Landlord on account of such
holdover. The provisions of this subsection shall not operate as a waiver by
Landlord of any right of re-entry provided in this Lease.

                                  ARTICLE XXIII
                               MEMORANDUM OF LEASE

         At the time of the execution of this Lease, Landlord and the Tenant
shall execute an instrument recordable in form containing those provisions
including but not limited to the Term, the commencement and expiration date, and
such other information as necessary or appropriate to protect the interests of
Tenant hereunder and to satisfy the notice of lease statute of 


<PAGE>


                                      -60-

Massachusetts. The Tenant may record the same.

                                  ARTICLE XXIV
                              SURRENDER OF PREMISES

         Upon the expiration of the Term or early termination thereof, Tenant
shall promptly peaceably yield up and surrender the Premises in a good and clean
condition, and in the same condition as Tenant is required to maintain the
Premises hereunder during the Term, reasonable wear and tear and damage by fire,
casualty or eminent domain excepted.

                                   ARTICLE XXV
                              ESTOPPEL CERTIFICATES

         Upon the written request of either party, at any time and from time to
time, Landlord and Tenant agree to execute and deliver to the other within
fifteen (15) business days after receipt of such request, a written instrument,
duly executed:

         (1)      Certifying that, if true, this Lease has not been modified and
                  is in full force and effect or, if there has been a
                  modification of this Lease, that this Lease is in full force
                  and effect as modified, stating such modifications;

         (2)      Specifying the date to which the rent has been paid;

         (3)      Stating whether or not to the best knowledge, information and
                  belief of the party executing such instrument, the other party
                  hereto is in default and, if such party is in default, stating
                  the nature of such default;

         (4)      Stating the commencement date of the Term; and

         (5)      Stating which options to extend the Term have been exercised, 
                  if any.

                                  ARTICLE XXVI
                              ADDITIONAL PROVISIONS

         26.1 BROKER - Landlord and Tenant warrant to each other that no
Broker(s) other than 


<PAGE>


                                      -61-


that specified in Section 1.1 of the Lease have been retained by the warranting
party in connection with the negotiation and consummation of this Lease. Each
party agrees to defend, indemnify and save the other harmless from and against
any and all claims for a commission arising out of a breach of the warranty made
by such party in the first sentence of this Section 26.1. This Section 26.1
shall survive the expiration or earlier termination of this Lease.

         26.2 BIND AND INURE - The obligations of this Lease shall run with the
land, and this Lease shall be binding upon and inure to the benefit of the
parties hereto and their respective successors and assigns except that only the
Landlord named herein shall be liable for obligations accruing before the
beginning of the Term and thereafter each successive owner of the Premises,
after giving to Tenant written notice of its assumption of the obligations of
Landlord under this Lease shall be liable only for obligations accruing during
the period of its ownership, said liability terminating as to future liability
upon termination of such ownership and passing to the successor in ownership and
the giving of such notice.

         26.3 PROVISIONS SEPARABLE - It is agreed that if any provisions of this
Lease shall be determined to be void by any court of competent jurisdiction in
Massachusetts, then such determination shall not affect any other provision of
this Lease, all of which other provisions shall remain in full force and effect;
and it is the intention of the parties hereto that if any provision of this
Lease is capable of two constructions, one of which would render the provision
void, and the other of which would render the provision valid, then the
provision shall have the meaning which renders it valid.

         26.4 ENTIRE AGREEMENT - This instrument contains the entire and only
agreement between the parties as to the Premises, and no oral statements or
representations or prior written matter not contained in this instrument shall
have any force or effect. This Lease shall not be 


<PAGE>


                                      -62-


modified in any way except by a writing subscribed by both parties.

         26.5 GOVERNING LAW - This Lease shall be governed by and construed and
enforced in accordance with the laws and courts of the Commonwealth of
Massachusetts.

         26.6 NO WAIVER - Failure of either party to complain of any act or
omission on the part of the other party, no matter how long the same may
continue, shall not be deemed to be a waiver of any rights hereunder. No waiver
by either party at any time, express or implied, or any breach of any provisions
of this Lease shall be deemed a waiver of a breach of any other provision of
this Lease or a consent to any subsequent breach of the same or any other
provision. If any action of any party shall require the consent or approval of
the other party, the consent to or approval of such action on any one occasion
shall not be deemed a consent to or approval of said action on any subsequent
occasion or a consent to or approval of any other action on the same or any
subsequent occasion, and such consent or approval shall not be unreasonably
withheld or delayed.

         26.7 RIGHTS SEPARATE - Any and all rights and remedies which either
party may have under this Lease or by operation of law, either at law or in
equity, upon any breach, shall be distinct, separate and cumulative and shall
not be deemed inconsistent with each other; no one of them whether exercised by
the other party or not, shall be deemed to be exclusive of any other, and any
two or more of all of such rights and remedies may be exercised at the same
time.

         26.8 SINGULAR AND PLURAL - Words and phrases used in the singular shall
be deemed to include the plural and vice versa, and nouns and pronouns used in
any particular gender shall be deemed to include any other gender.

         26.9 HEADINGS - The various terms which are defined in Articles of this
Lease or are defined in Exhibits annexed hereto shall have the meanings
specified in such Articles and such 


<PAGE>


                                      -63-


Exhibits for the purposes of this Lease and all agreements supplemental thereto,
unless the context clearly indicates the contrary.

         26.10 PARKING - Tenant's occupancy of the Premises shall include the
exclusive use of 341 parking spaces located upon the Lot.

         26.11 NON-RECOURSE - Tenant agrees to look solely to Landlord's then
equity interest in the Premises and the proceeds thereof at the time owned for
recovery of any judgment from Landlord; it being agreed that neither Landlord
(original or successor), nor any partner (general or limited), associate,
participant, principal (disclosed or undisclosed), agent, employee, trustee or
other fiduciary, beneficiary, officer, or other person or entity in or of any
partnership, association, joint venture, corporation or other entity, trust, or
estate from time to time owning Landlord's interest in this Lease, shall ever be
personally liable for any such judgment or for the payment of any monetary
obligation to Tenant with respect to matters arising out of this Lease (it being
agreed by Tenant that such exoneration from personal liability is and shall be
absolute and complete with no exception whatsoever). With respect to any
services to be furnished or obligations to be performed by Landlord to Tenant,
except with respect to the negligence of Landlord, its employees, agents or
contractors, Landlord shall never be liable for failure to furnish or perform
the same when prevented from doing so by strike or lockout (not limited to the
Premises or the Office Park), breakdown, accident, order or regulation of or by
any governmental authority, or failure of supply, or inability by the exercise
of reasonable diligence to obtain supplies, parts or employees necessary to
furnish such services, or because of war or other emergency, or for any act of
God or other Force Majeure, as defined below, causes beyond Landlord's
reasonable control, or for any cause due to any act or negligence of Tenant,
Tenant's invitees, customers, servants, agents, employees, licensees or any
person claiming by, through or 


<PAGE>


                                      -64-


under Tenant.

         With respect to any obligations to be performed by Tenant to Landlord,
other than the payment of rent and other sums due under this Lease, except with
respect to the negligence Tenant, its employees, agents or contractors, Tenant
shall never be liable for failure to furnish or perform the same when prevented
from doing so by strike or lockout (not limited to the Premises or the Office
Park), breakdown, accident, order or regulation of or by any governmental
authority, or failure of supply, or inability by the exercise of reasonable
diligence to obtain supplies, parts or employees necessary to furnish such
services, or because of war or other emergency, or for any act of God or other
Force Majeure, as defined below, causes beyond Tenant's reasonable control, or
for any cause due to any act or negligence of Landlord, Landlord's invitees,
customers, servants, agents, employees, licensees or any person claiming by,
through or under Landlord.

         26.12 FORCE MAJEURE - As used in this Article and elsewhere in this
lease , "Force Majeure" shall mean a time extension equal to that of any delays
due to (i) acts of God, (ii) changes in governmental regulations, (iii)
casualty, (iv) strike or other labor difficulties (not limited to the Premises
or the Office Park), (v) unusual weather conditions, (vi) inability despite the
exercise of diligence, to obtain supplies, parts or employees to furnish
services, or (vii) other acts reasonably beyond Landlord's or Tenant's control,
but in no event shall the term include economic or financing difficulties.

         26.13    INTENTIONALLY DELETED

         26.14 CONFIDENTIALITY - This Lease document is a confidential document
by and between Landlord and Tenant and shall not be disclosed, copied,
distributed or circulated to any person(s) other than to such parties, and their
respective employees, agents, consultants, contractors, 


<PAGE>


                                      -65-


architects, brokers, lenders, shareholders, directors and investors, mortgagees,
successors or assigns, or to any prospective sublessees and assignees of Tenant,
and to the legal counsel and accountants of any of the foregoing persons or
entities, without the prior written consent of the Landlord, which shall not be
unreasonably withheld or delayed. This Section 26.14 is not applicable when
disclosure, copying, distribution or circulation of this Lease document is
necessitated by disclosure requirements due to Tenant's nature as a public
corporation, if applicable, or by other requirements of Law or by order of the
court.

         26.15 SECURITY DEPOSIT Landlord acknowledges receipt of a letter of
credit in the amount of $560,625 as security for Tenant's obligations under the
Lease (the "Security Deposit"). The Security Deposit will decrease by one-fifth
(1/5) each year during the five (5) year Lease Term, commencing on the first
anniversary of the Commencement Date and on each successive anniversary of the
Commencement Date (each, a "Reduction Date"). On each Reduction Date, Landlord
shall return the Security Deposit to Tenant provided that Tenant has delivered a
replacement (or amended) letter of credit, in an amount reduced by twenty
percent (20%) from the amount of the previous letter of credit. After the
reduction of the Security Deposit to $0, Tenant shall have no further obligation
to maintain a Security Deposit hereunder.

         If all or any part of the Security Deposit is applied to an obligation
of Tenant hereunder, Tenant shall immediately, upon request by Landlord, restore
the Security Deposit to its original amount. Tenant shall not have the right to
call upon Landlord to apply all or any part of the Security Deposit to cure any
default or fulfill any obligation of Tenant, but such use shall be solely in the
discretion of Landlord. Upon any conveyance by Landlord of its interest under
this Lease, the Security Deposit may be delivered by Landlord to Landlord's
grantee or transferee. Upon any such delivery, Tenant hereby releases Landlord
herein named of any and all liability 


<PAGE>


                                      -66-


with respect to the Security Deposit, its application and return, and Tenant
agrees to look solely to such grantee or transferee. It is further understood
that this provision shall also apply to subsequent grantees and transferees.

         IN WITNESS WHEREOF, the parties hereto have duly executed this Lease as
of this 18TH day of AUGUST, 1997


Tenant:  NetScout Systems, Inc.       LANDLORD: Michelson Farm - Westford
                                      Technology Park IV Limited Partnership

By: /s/ Charles Tillett               By: The Gutierrez Company as the sole 
    -------------------                   General Partner


Its: VP FINANCE ADMINISTRATION        By:  /s/ Arturo Gutierrez   
     -------------------------             ---------------------------
                                      Its: President
                                           ---------------------------


<PAGE>


                                      -67-


                                    EXHIBIT A

                                 [EASEMENT PLAN]

<PAGE>


                                      -68-


                                   EXHIBIT "B"
                              RULES AND REGULATIONS

         1.           Tenant must, upon the termination of its tenancy, restore
                      to Landlord all keys of offices and toilet rooms, either
                      furnished to or otherwise procured by Tenant, and in the
                      event of the loss of any keys so furnished, Tenant shall
                      pay to landlord the replacement cost.

         2.           Canvassing, soliciting and peddling in the Building or on 
                      the Lot or in the Office Park are prohibited, and Tenant 
                      shall cooperate to prevent the same.

         3.           Tenant shall comply with all reasonable security measures
                      from time established by Landlord and of which Tenant
                      receives written notice, for the Lot or Office Park, so
                      long as (i) the same do not breach or violate Tenant's
                      lights under the Lease or the requirements of any
                      governmental security regulations to which Tenant is
                      subject, and (ii) such reasonable security measures do not
                      deprive Tenant of reasonable access to the Premises at all
                      times or otherwise unreasonably interfere with Tenant's
                      use or occupancy of the Premises.

         4.           Tenant shall comply with the Office Park Covenants 
                      attached hereto as Exhibit "C" to which the Lot is 
                      subject.


<PAGE>


                                      -69-


                                   EXHIBIT "C"

                    MICHELSON FARM - WESTFORD TECHNOLOGY PARK
                         OFFICE/RESEARCH AND DEVELOPMENT
                                 PARK COVENANTS

         Landlord agrees with Tenant to enforce, or cause to be enforced, and
comply with these Park Covenants with all due diligence to preserve the quality
and appearance of the Park (as hereinafter defined).

         The land is located in an approximately 85 acre office/research and
development park, commonly known as Westford Technology Park (hereinafter,
together with any additions thereto, called the "Park").

         All lots of land comprising the Park (which lots are individually
called the "Parcel" and collectively the "Parcels") are subject to the following
restrictions which shall bind Michelson Farm Westford Technology Park Trust
("Grantor") as owner of the Park and its successors in title, including but not
limited to Landlord and its successor.

         A.       All parcels shall have facilities for parking, loading and
                  unloading sufficient to serve any uses to the Parcels without
                  using adjacent streets for such purpose. On -street parking
                  shall be prohibited. All parking, trucking and vehicular
                  maneuvering areas for a Parcel shall be contained within such
                  Parcel.

         B.       No exterior loading platforms shall be visible from any
                  primary way or proposed primary way serving the Park.
                  Screening and planting may be used for this purpose.

         C. No open or outside storage shall be done on any Parcel.

         D.       Signs shall conform to the sign ordinances of the Town. Any
                  variance from such ordinance granted by the Town must also be
                  approved by Grantor in the manner provided below in Section I.

         E.       No condition or use of any Parcel will be permitted which is
                  objectionable by reason of noise, odor, vibration, smoke,
                  radiation, the hazardous nature of the use, or the violation
                  of environmental standards adopted by the Town, the


<PAGE>


                                      -70-


                  Commonwealth, the Federal Government or any Court.

         F.       All utilities serving a Parcel shall be placed underground,
                  unless prohibited by the utility company. Any exterior
                  lighting on a Parcel shall either be indirect or of such
                  controlled focus and intensity as not to disturb street
                  traffic or the occupancy of any adjacent Parcel.

         G.       The exterior appearance of any buildings in the Park,
                  including landscaping thereon, shall be kept neat and orderly
                  and free from litter.

         H.       No building, exterior sign, fence, wall, exterior lighting or
                  other structure shall be erected or allowed to remain on any
                  portion of the Park or exterior structural alteration or
                  addition made, except pursuant to plans approved in writing by
                  Grantor as to landscaping, parking and architectural
                  conformity with existing buildings in the Park.

         I.       The Grantor may from time to time by written instrument in
                  recordable form grant variances from any one or more of these
                  restrictions (except Restriction H for which variances may not
                  be granted) where the Grantor reasonably determines that the
                  variance can be granted without substantial detriment to the
                  intent and purpose of the restrictions and without substantial
                  detriment to the Land, and portions of the Park theretofore
                  built upon.

         J.       Written approval by the Grantor as to any buildings, signs,
                  structures, alterations, additions and landscaping approved by
                  Grantor in good faith shall be conclusive evidence of
                  compliance with these restrictions. The Grantor agrees to
                  furnish to any grantee as evidence of such compliance.

         K.       The term "Grantor, as herein used, shall mean the Michelson
                  Farm - Westford Technology Park Trust and any successors in
                  title to whom the Grantor has expressly granted of record the
                  rights to enforce these restrictions.


<PAGE>


                                      -71-


                                   EXHIBIT "D"
                     MICHELSON FARM-WESTFORD TECHNOLOGY PARK
                                 QUITCLAIM DEED

         ARTURO J. GUTIERREZ AND JOHN A. CATALDO, CLASS A TRUSTEES, AND JOHN
PIKE AND THOMAS E. LEGGAT, CLASS B TRUSTEES, TRUSTEES OF THE MICHELSON
FARM-WESTFORD TECHNOLOGY PARK TRUST, under Declaration of Trust dated October 1,
1984, recorded with the Middlesex North District Registry of Deeds in Book 2863,
Page 235, having an address c/o The Gutierrez Company, One Wall Street,
Burlington, Massachusetts 01803 (hereinafter referred to as the "Grantor"), for
consideration paid and in full consideration of Ten Dollars ($10.00) grants to
MICHELSON FARM - WESTFORD TECHNOLOGY PARK IV LIMITED PARTNERSHIP, a
Massachusetts limited partnership, having an address c/o The Gutierrez Company,
One Wall Street, Burlington, Massachusetts 01803 (hereinafter collectively,
referred to as the "Grantee"), with QUITCLAIM COVENANTS, a certain parcel of
land together with the buildings and improvements situated thereon, located in
Westford, Middlesex County, Massachusetts, being shown as Lot 4B on a plan
entitled "Definitive Plan of Land, Westford Technology Park in Westford,
Massachusetts", Prepared by Howe Surveying Associates, Inc., Scale 1" = 100',
dated June 3, 1996, revised July 12, 1996 and recorded with the Middlesex North
Registry of Deeds on at Plan Book 192, Plan 24 (the "Plan"). Said Lot 4B
contains 362,973 square feet of land, more or less, according to said Plan.

         Said parcel is conveyed subject to and with the benefit of all rights,
easements, restrictions and reservations of record, in so far as in force and
applicable.


<PAGE>


                                      -72-


         For reference to Grantor's title, see deed of Michelson Farm-Westford
Technology Park IV Limited Partnership Trust dated September 4, 1996, recorded
herewith, and see deed of Michelson Farm-Westford Technology Park Trust, dated
June 18, 1987, recorded with said Deeds in Book 4117, Page 156.

         EXECUTED under seal this 4th day of September, 1996.


                                        MICHELSON FARM - WESTFORD
                                        TECHNOLOGY PARK TRUST

                                        /s/ Arturo J. Gutierrez
                                        ----------------------
                                        Arturo J. Gutierrez, as Class A Trustee
                                        and not individually

                                        /s/ John Pike
                                        -------------
                                        John Pike, as Class B Trustee and not
                                        individually

                          COMMONWEALTH OF MASSACHUSETTS


Suffolk, ss.                                                   September 4, 1996

         Then personally appeared the above-named Arturo J. Gutierrez, Class A
Trustee of Michelson Farm - Westford Technology Park Trust, and acknowledged the
foregoing instrument to be his free act and deed as Trustee as aforesaid, before
me,

                                                         /s/ A. P. Gottlieb
                                                         ------------------
                                                          Notary Public
                                                          My commission expires:


                          COMMONWEALTH OF MASSACHUSETTS

Suffolk, ss.                                                   September 4, 1996

         Then personally appeared the above-named John Pike, Class B Trustee of
Michelson Farm - Westford Technology Park Trust, and acknowledged the foregoing
instrument to be his free act and deed as Trustee as aforesaid before me,


<PAGE>


                                      -73-


                                                      /s/ Marie E. Wolf
                                                       Notary Public
                                                       My commission expires:


<PAGE>


                                      -74-


                                   Exhibit "E"

                        SUBORDINATION, NONDISTURBANCE AND
                              ATTORNMENT AGREEMENT

         AGREEMENT made this 18th day of August, 1997 by and among THE
PRUDENTIAL INSURANCE COMPANY OF AMERICA, a New Jersey corporation, with an
office at One Ravinia Drive, Suite 1400, Atlanta, Georgia 30346-2110
("Mortgagee"), NETSCOUT SYSTEMS, INC., with an address at 321 Billerica Road,
Chelmsford, Massachusetts 01824 ("Tenant"), and MICHELSON FARM-WESTFORD
TECHNOLOGY PARK IV LIMITED PARTNERSHIP, a Massachusetts limited partnership,
with an address at c/o The Gutierrez Company, One Wall Street, Burlington,
Massachusetts 01803 ("Borrower").

                              W I T N E S S E T H:

         WHEREAS, Mortgagee is the holder of a mortgage from Borrower dated
March 10, 1988, and a separate assignment of lessor's interest in leases and
assignment of rentals, both dated March 10, 1988, which documents are recorded
with Middlesex North District Registry of Deeds in Book 4435, beginning at Page
155, and have been subsequently amended by instruments recorded in said registry
(said mortgage as amended are herein collectively referred to as the
"Mortgage"), which Mortgage covers certain premises in Westford, Middlesex
County, Massachusetts, as more fully described therein ("Mortgaged Property");
and

         WHEREAS, by virtue of a lease (the "Lease") dated as of August 18,
1997, between Borrower, as Landlord therein, and Tenant, as Tenant therein, true
and correct copies of which have been delivered to Mortgagee, Tenant has leased
from Borrower the Premises, as defined in the Lease, which Premises form a part
of the Mortgaged Property.


<PAGE>


                                      -75-


                                 NOW THEREFORE:

         In consideration of the sum of One Dollar ($1.00) by each party in hand
said to the other, receipt of which is hereby acknowledged, and in consideration
of the mutual covenants and agreements hereinafter contained, the parties
hereto, intending to be legally bound hereby, hereby agree as follows:

         1.       Tenant hereby agrees;

         (a) subject to and to the extent not inconsistent with this Agreement,
the Lease and Tenant's leasehold estate and any and all estates, options, and
rights therein contained or created thereby are, and shall be and remain,
subject and subordinate in all respects to the lien of the Mortgage and to all
of the terms, conditions and provisions thereof, to all advances made or to be
made thereunder, and to any renewals, extensions, modifications,
consolidations-or replacements thereof.

         (b) from time to time, upon request by written notice from Mortgagee,
it shall within fifteen business days of receipt of such a request provide
Mortgagee with an estoppel certificate, in the form attached to the Lease as
Exhibit G, certifying to the best knowledge, information and belief of Tenant
that there is no default on the part of Borrower under the Lease or, if Borrower
is in default, stating the nature of such default.

         (c) it will forward to Mortgagee in the manner provided herein for
notices, copies of any notice of any default of Borrower pursuant to the Lease
given or made by Tenant;

         (d) without the prior written consent of Mortgagee, (i) the Lease shall
not be terminated by Tenant except as provided therein nor shall Tenant be
released from liability thereunder in connection with any assignment or
subletting in accordance with Article XVII of the Lease nor shall Tenant
surrender the Lease or the Mortgaged Property except incident to a


<PAGE>


                                      -76-

termination provided for in the Lease, and (ii) the Lease shall not be
subordinated to any encumbrance hereafter placed on the Mortgaged Property.
Landlord shall not enforce against Tenant any obligation under the Lease so to
subordinate without obtaining Mortgagee's prior written consent.

         (e) in the event of any default by Borrower under the Lease which would
give Tenant the right to terminate the Lease, Tenant will not exercise such
right until it shall have given written notice of such act or omission to
Mortgagee ("Tenant's Notice"), and (ii) if it so elects, Mortgagee shall have
the right (but not the obligation) to cure any default by Borrower under the
Lease, including, if necessary to cure defaults, the right of access to the
Mortgaged Property, subject to compliance by Mortgagee with all of the notice
and other restrictions upon access by Borrower to the Mortgaged Property under
the Lease, including Section 12.3 thereof. Tenant shall not take any such action
to terminate the Lease thereunder unless Mortgagee, after receipt of Tenant's
Notice, falls to cure, or cause to be cured, the specified default within the
time allowed therefor for cure by Borrower under the Lease plus a reasonable
time thereafter if Mortgagee shall within thirty days of receipt of Tenant's
Notice give Tenant notice ("Mortgagee's Notice") of its intention to, and
commences and continues to remedy such act or omission, or cause the same to be
remedied with reasonable diligence. "Reasonable time" as used herein includes a
reasonable time necessary with reasonable diligence to obtain possession of the
Mortgaged Property if the default cannot be cured without such possession.
Tenant shall accept such cure as if made by Borrower. Nothing in this Paragraph
1 (e) shall, however, in any way limit or affect Tenant's right at law or in
equity to cure any default of Borrower and deduct the cost thereof from rent
due;


<PAGE>


                                      -77-


         (f) in the event that Mortgagee or Purchaser (hereinafter defined), or
anyone claiming from or through Mortgagee, shall enter into and lawfully become
possessed of the Mortgaged Property, or shall succeed to the rights of Borrower
under the Lease, either through foreclosure of said Mortgage or otherwise,
Tenant shall attorn to, and recognize, Mortgagee or Purchaser as its Landlord
under the Lease for the unexpired balance of the term of the Lease and any
extension thereof, subject to all of the terms and conditions of the Lease,
which shall continue in full force and effect as a direct Lease between
Mortgagee or Purchaser and Tenant;

         (g) Tenant shall make all payments payable by Tenant under the Lease
directly to Mortgagee or Purchaser subsequent to receipt of Mortgagee's or
Purchaser's written instructions by notice to Tenant and Borrower agrees that
such payments shall be deemed paid under the Lease with the same effect as if
paid directly by Tenant to Borrower.

         (h) Mortgagee or Purchaser shall have no responsibility, liability or
obligation to cure any defaults by Borrower under the Lease, nor be subject to
claims, defenses or offsets under the Lease or against Borrower possessed by
Tenant and which arose or existed prior to foreclosure of the Mortgage or deed
given in lieu of foreclosure or entry and taking possession of the Mortgaged
Property by Mortgagee or Purchaser, except to the extent hereinafter provided.

         (i) the institution of any action or other proceedings by Mortgagee
under the Mortgage in order to realize upon the Borrower's interest in the
Mortgaged Property shall not by operation of law, or otherwise, result in the
cancellation or termination of the Lease or Tenant's obligations thereunder and
Mortgagee may, at its election, subordinate the Mortgage to the Lease without
the consent of Borrower or Tenant.

         (j) during the period of time that Mortgagee has given Mortgagee's
Notice of its intention, and is attempting with reasonable diligence, to effect
a cure of any condition of the 


<PAGE>


                                      -78-


Mortgaged Property, but is prevented by reason of operation of law or court
order (the "Prevention Period") from effecting such cure, the time to remedy any
such condition prior to any right of Tenant to terminate the Lease shall be
extended by the number of days in the Prevention Period, unless the Prevention
Period is caused by Mortgagee's negligence, willful misconduct or violation of
any laws, statutes, ordinances, rules or regulations applicable to the Mortgaged
Property or to the enforcement of Mortgagee's rights under the Mortgage.

         (k) Upon any foreclosure of the Mortgage or deed given in lieu of
foreclosure or entry and taking possession of the Mortgaged Property by
Mortgagee or Purchaser, Tenant agrees to reissue the letter of credit
contemplated by Section 26.15 of the Lease to Mortgagee or Purchaser, provided
the existing letter of credit issued to Landlord is simultaneously surrendered
to Tenant or to the issuing bank or has otherwise previously expired, terminated
or been so surrendered.

         2. Mortgagee hereby consents to, and approves and recognizes Tenant's
rights under the Lease and agrees that so long as Tenant is not in default
(beyond all applicable periods given Tenant under the Lease to cure such
default):

         (i) Tenant's possession and occupancy of the Mortgaged Property and
Tenant's rights and privileges under the Lease, or any extension thereof which
may be effected in accordance with the terms of the Lease, shall not be
disturbed, affected or impaired by, nor will the Lease or the term of the Lease
be terminated or otherwise affected by, (a) any suit, action or proceeding upon
the Mortgage or the note or other obligation secured thereby, or for the
foreclosure of the Mortgage or the enforcement of any rights under the Mortgage
or any other documents held by Mortgagee, or by any judicial sale or execution
or other sale of the Mortgaged Property, or by any deed given in lieu of
foreclosure, or by the exercise of any other rights given to Mortgagee by any
other documents or as a matter of law, or (b) any default under the Mortgage or
the note 


<PAGE>


                                      -79-


or other obligation secured thereby;

         (ii) Mortgagee shall not, except as required by law, name or join
Tenant as party to any action, suit or proceeding brought to foreclose the
Mortgage or to enforce anY rights under the Mortgage or any other documents held
by Mortgagee or the note or other obligation secured thereby.

         (iii) the amount of any insurance proceeds, less adjusters' fees and
other reasonable expenses of collection, paid or payable with respect to the
Mortgaged Property and received by Mortgagee shall be applied to the repair and
restoration of the Mortgaged Property, subject to reasonable construction loan
type conditions, provided that Tenant has executed an agreement with Borrower
and Mortgagee at or prior to the commencement of such repair or restoration,
extending for a reasonable time, if necessary, the time periods for such repair
or restoration set forth in Article XIII of the Lease;

         (iv) after a condemnation proceeding, if the Mortgaged Property is
capable of being restored, in Mortgagee's reasonable discretion, to a viable
economic unit, the amount of any condemnation awards, less all costs and
expenses of collection, including reasonable attorneys' fees, paid or payable
with respect to the Mortgaged Property and received by Mortgagee shall be
applied to the repair and restoration of the Mortgaged Property, subject to
reasonable construction loan type conditions, provided that Tenant has executed
an agreement with Borrower and Mortgagee, at or prior to the commencement of
such repair or restoration, extending for a reasonable time, if necessary, the
time periods for such repair or restoration set forth in Article XIII of the
Lease;

         (v) During any period in which Mortgagee, its successors and assigns,
or


<PAGE>


                                      -80-


 Purchaser, hold title and possession of the Mortgaged Premises, Mortgagee,
its successors and assigns or Purchaser, shall be bound by and perform, fulfill
and observe all of the agreements and obligations of Borrower under the Lease
which shall continue in full force and effect as a direct Lease between
Mortgagee, its successors and assigns or Purchaser, and Tenant, but Mortgagee
and its successors and assigns or Purchaser shall not, however, be:

         (a) bound by any rent or other payment which Tenant might have paid
more than thirty (30) days in advance of the time stipulated for payment under
the Lease;

         (b) bound by any amendment or modification of the Lease made without
its written consent, which Mortgagee agrees shall not be unreasonably withheld,
conditioned or delayed;

         (c) liable for any act or omission of any prior landlord (including
Borrower) unless such act or omission continues without cure within a reasonable
time after Mortgagee, its successors or assigns, or Purchaser, take title and
possession to the Mortgaged Premises;

         (d) subject to any offset or defense which Tenant might have against
any prior landlord (including Borrower) except for any offset expressly
permitted by the terms of the Lease; and

         (e) liable to Tenant for return or reduction of the letter of credit
delivered to Landlord as a Security Deposit under Section 26.15 of the Lease,
unless such letter of credit has been delivered to Mortgagee or Purchaser or
reissued to Mortgagee or Purchaser under the provisions of Paragraph 1(k) above.

         (vi) Mortgagee or Purchaser shall accept attornment made by Tenant 
pursuant to the provisions of paragraph 1 hereof. 

         3. Any notice, demand or consent hereunder shall be in writing and
shall be given or mailed by mailing the same by registered or certified mail,
return receipt requested, addressed, if intended for Mortgagee, to The
Prudential Insurance Company of America, Commercial Loan


<PAGE>


                                      -81-


Division, P.O. Box 16082, Van Nuys, California 91410-0082, Attn: Servicing
Department with a copy to The Prudential Insurance Company Of America, One
Ravinia Drive, Suite 1400, Atlanta, Georgia 30346 Attn: Customer Service, Re:
Loan No. 7 501 325, and if intended for Tenant, addressed to Tenant at the
address set forth on the first page of this Agreement with a copy to: Testa,
Hurwitz and Thibeault, LLP, 125 High Street, High Street Tower, Boston,
Massachusetts, 02110, Attn: Real Estate Department, and if intended for
Borrower, addressed to Borrower at the address set forth in the first page of
this Agreement with a copy to Hinckley, Allen & Snyder, One Financial Center,
Suite 4600, Boston, Massachusetts 02108 Attn: Paul A. Headstrom, Esquire. Any
party may designate a new address by notice in writing to the other parties. Any
notice given in accordance herewith shall be effective upon deposit in the
United States mails in accordance herewith except that where any time period
commences hereunder or under the Lease from notice, such time period shall
commence when postal records indicate delivery was made or first attempted.

         4. Prior to foreclosure of the Mortgaged Property or any deed given in
lieu of foreclosure or entry under the Mortgage and taking possession of the
Mortgaged Property by Mortgagee (collectively or individually, "Foreclosure"),
Mortgagee shall have only such rights of Borrower as are necessary to preserve
the integrity of the Lease as security and such other rights as are set forth in
this Agreement. Upon Foreclosure, Mortgagee shall have all rights of Borrower
under the Lease. Notwithstanding the provisions of Paragraph 1 (a) of this
Agreement but subject to all other provisions of this Agreement, in the event of
any inconsistency between the Lease and the Mortgage, as between Tenant and
Mortgagee, the Lease shall control and be binding upon Mortgagee, except as
follows. Upon Foreclosure, Mortgagee shall not be bound by, nor have any
obligations under, the environmental indemnity of Borrower contained in 


<PAGE>


                                      -82-


Section 16.3 of the Lease. Mortgagee does agree upon Foreclosure, for so long as
Mortgagee owns the Mortgaged Property, to comply with all Hazardous Waste Laws
(as defined in the Lease).

         5. All trade fixtures, equipment and other property owned by Tenant
located or installed in or on the Mortgaged Property regardless of the manner or
mode of attachment, shall be and remain the property of Tenant and may be
removed by Tenant at any time subject to the terms of the Lease. In no event
(excepting only a judgment lien following a default under the Lease at a time
when Mortgagee shall have succeeded the rights of Borrower as landlord ) shall
Mortgagee have any liens, rights or claim in Tenant's property; and Mortgagee
expressly waives all rights of levy, distraint, or execution with respect to
said property (other than a judgment lien).

         6. This Agreement shall be binding upon and inure to the benefit of the
successors and assigns of each of the parties hereto, including grantees under
any deed given in lieu of foreclosure, purchasers at a foreclosure sale, or any
party acquiring an interest in the Mortgaged Property by any other method, and
their successors and assigns (such grantees, purchasers at foreclosure and
acquiring parties and their respective successors and assigns collectively
referred to herein as "Purchaser").

         This Agreement shall be governed by, and construed under the laws of
the Commonwealth of Massachusetts.


<PAGE>


                                      -83-


         IN WITNESS WHEREOF, the parties hereto have caused the execution hereof
as a sealed instrument as of the day and year first written above.

                                            TENANT:


                                            NETSCOUT SYSTEMS, INC.

                                            By: /s/ Charles W. Tillett
                                                ------------------------------
                                            Title: VP Finance & Administration

                                            MORTGAGEE:

                                            THE PRUDENTIAL INSURANCE
                                            COMPANY OF AMERICA

                                            By:[Illegible Signature]
                                               --------------------
                                            Vice President

                                            LANDLORD/BORROWER:

                                            MICHELSON FARM-WESTFORD
                                            TECHNOLOGY PARK IV
                                            LIMITED PARTNERSHIP

                                            By: THE GUTIERREZ COMPANY,
                                                 general partner

                                            By: /s/ Arturo J. Gutierrez
                                                -----------------------
                                            Title: President


<PAGE>


                                      -84-


                          COMMONWEALTH OF MASSACHUSETTS


Middlesex, ss:                                                 August 18, 1997

         Then personally appeared before me the above-named Charles Tillett of
NetScout Systems, Inc. and acknowledged the foregoing instrument to be the free
act and deed of NetScout Systems, Inc.

                                              [Illegible Signature]
                                               -------------------
                                              Notary Public
                                              My Commission expires: 6/7/02


                                STATE OF GEORGIA

Dekalb, ss:                                                    August 26, 1997

         Then personally appeared before me the above-named David A. Graham,
Vice President of The Prudential Insurance Company of America and acknowledged
the foregoing instrument to be the free act and deed of The Prudential Insurance
Company of America

                                              [Illegible Notary Signature]
                                               --------------------------

                          COMMONWEALTH OF MASSACHUSETTS

Middlesex, ss:                                                 August 28, 1997

         Then personally appeared before me the above-named Arturo J. Gutierrez
of The Gutierrez Company, General Partner of Michelson Farm-Westford Technology
Park IV Limited Partnership and acknowledged the foregoing instrument to be the
free act and deed of said Limited Partnership.

                                              /s/ J. Stevens
                                              --------------
                                              Notary Public


<PAGE>


                                      -85-


                                   EXHIBIT "F"
                              INTENTIONALLY DELETED


<PAGE>


                                      -86-


                                   EXHIBIT "G"
                              ESTOPPEL CERTIFICATE

         THIS CERTIFICATE is made to

with respect to a Lease between
                   as Landlord and the undersigned, covering a building located
in such lease being dated                 , as amended by (list all amendments):

         The undersigned has been advised that
                  as Trustee as aforesaid (the "Bank"), is about to enter into a
transaction whereby the Bank is making a loan secured by the aforesaid real
estate and the Lease to the undersigned, and under which the Bank may acquire an
ownership interest in such real estate. In connection with this transaction, the
entire interest of the Landlord under the Lease to the undersigned will be
assigned to the Bank. The undersigned acknowledges that the Bank is and will be
relying upon the truth, accuracy and completeness of this letter in proceeding
with the transaction described above.

         The undersigned, for the benefit of the Bank, their successors and
assigns, hereby certifies, represents, warrants, agrees and acknowledges that:

1.       The Lease is in full force and effect in accordance with its terms
         without modification or amendment except as noted above and the
         undersigned is the holder of the Tenant's interest under the Lease.

2.       The undersigned is in possession of all of the Premises described in
         the Lease under and pursuant to the Lease and is doing business
         thereon; and the Premises are completed as required by the Lease.

3.       The undersigned has no claims or offsets with respect to any of its
         obligations as Tenant under the Lease, and neither the undersigned nor
         the Landlord is claimed to be in default under the Lease.

4.       The undersigned has not paid any rental or installments thereof in 
         advance of the due date as set forth in the Lease.

5.       The undersigned has no notice of prior assignment, hypothecation or
         pledge of rents of the Lease or the Landlord's interest thereunder or
         of the Tenant's interest thereunder.

6.       The term of the Lease has commenced and is presently scheduled to
         expire on. If there are any rights of extension or renewal under the
         terms of the Lease, the same have not, as of the date of this letter,
         been exercised.

7.       Until such time as the Bank shall become the Landlord, if the
         undersigned should assert a 


<PAGE>


                                      -87-


         claim that the Landlord has failed to perform an obligation to the
         undersigned under the terms of the Lease or otherwise, notice thereof
         shall promptly be furnished to the Bank; and the undersigned agrees
         that the undersigned will not exercise any rights which the undersigned
         might otherwise have on account of any such failure until notice
         thereof has been given to the Bank, and the Bank has had the same
         opportunity to cure any such failure as the Landlord may have under the
         terms of the Lease, or such additional time as may be set forth in the
         Lease.

8.       Each of the statements set forth in Paragraphs 1 through 7 are true, 
         accurate and complete except as follows (state specifically any
         exception):

DATED:
ATTEST:
BY:                                        By:
   --------------------------------           ----------------------------------


<PAGE>


                                      -88-


                                   EXHIBIT "H"
                          LANDLORD, TENANT, CONTRACTOR
                              CHANGE PROPOSAL FORM

Project:
            ---------------------------------------------
                                                              R        NR
            ---------------------------------------------     ---------  -------
Proposal No.                           Date                   BB       TW
            --------------------------     --------------       -------  -------
From: (Landlord)
                -----------------------------------------

To: (Contractor)
                -----------------------------------------
CC: (Tenant)
            ---------------------------------------------

--------------------------------------------------------------------------------
Step 1:    Contractor:     Provide an estimate for the described work.
           Architect:      Develop proper plans and specifications to clarify 
                           described work.
           DESCRIPTION:    (List Drawings)

           Landlord:                              Reason:
                    -----------------------------        -----------------------
                      John A. Cataldo, Trustee

--------------------------------------------------------------------------------
Step 2:    Contractor:     Provide with work as definitive plans become 
                           available.

           Landlord:                               Date:
                    -------------------------------     ------------------------
                      John A. Cataldo, Trustee

--------------------------------------------------------------------------------
Step 3:    Cost of Work
           a.  Cost of the work                       $
               (See attached breakdown)                ---------------
           b.  Add construction fee at 4%             $                         
                                                       ---------------
           Total Cost of Work                         $
                                                       ---------------

Submitted by:
             ------------------------------------------       ------------------
Dennis G. Bailey, Vice President & Construction Manager       Date

--------------------------------------------------------------------------------
Step 4: The submitted Cost of Work has been reviewed and is (not) approved.

        -----------------------------------           ----------------
                  Architect                           Date
               Design Fees -                          $
                                                       ---------------
               TOTAL COST OF PROPOSAL                 $
                                                       ---------------


<PAGE>


                                      -89-



--------------------------------------------------------------------------------
Step 5:    FINAL ACTION
           a.  The Tenant _______________________ Hereby agrees to reimburse the
                                    Name of Firm
           Landlord the Total Cost of Proposal shown in Step 4 above.


           ----------------------------------        ----------------
           Authorized Tenant's Representative        Date

           b.   This bulletin is approved (rescinded) and the work above is
                (not) to be performed. Cost of this work shall be included in
                Change Order No.________


           ----------------------------------        ----------------
                             Landlord                Date


<PAGE>


                                      -90-


                                   EXHIBIT "I"

                              Intentionally Deleted

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