Document:

<PAGE>
                                                                    EXHIBIT 10.5

                                LEASE AGREEMENT
                                ---------------

     THIS LEASE AGREEMENT made and entered into as of the 25th day of November,
1985, by and between Roger G. Little, Trustee of SPI-Trust, under a declaration
of trust, dated May 3, 1976, and recorded with Middlesex South District
Registry of Deeds, Book 12970, Page 625, having a mailing address at Patriots
Park, Bedford, Massachusetts 01730 (the "Landlord") and Millipore Corporation, a
Massachusetts corporation, with an address at 80 Ashby Road, Bedford,
Massachusetts 01730 (the "Tenant").

                             W I T N E S S E T H:
                             - - - - - - - - - -

     1.   Lease of Premises.  Subject to all of the provisions herein contained,
          -----------------
and in consideration of the rentals to be paid to Landlord by Tenant, and the
other covenants and agreements to be kept and performed by Tenant hereunder, as
hereinafter set forth, Landlord hereby leases to Tenant, and Tenant hereby
leases from Landlord, the premises situated in Bedford, Middlesex County,
Massachusetts, located on the Westerly side of Wiggins Avenue, known as Patriots
Park, including the real estate bounded and described as set forth in Exhibit A
attached hereto and made a part hereof (the "Real Estate"); an existing one
story building containing approximately 44,000 square feet (the "Building") and
a two story addition containing approximately 100,000 square feet currently
under construction (the "Addition" and, collectively with the Real Estate and
the Building, the "Premises") to be used by Tenant for any lawful purpose.

     2.   Term.  The term of this Lease Agreement shall be for a period of
          ----
twenty (20) years, beginning, subject to the provisions of Section 3(c), on the
1st day of December, 1985 (the "Commencement Date") and, unless terminated as
herein provided, continuing until expiration on the 30th day of November, 2005.

     3.   Completion of Addition; Delayed Commencement.  (a) Landlord agrees to
          -------------------------------------------
proceed diligently with the construction of the Addition in substantial
conformity with the plans, drawings and construction specifications (including
the indicated revision thereof) listed on Exhibit B hereto and made a part
hereof (the "Specifications"). Landlord represents, warrants and covenants that
the Addition, when completed: (i) shall conform to the Specifications, except
that if specific materials or supplies shall become impractical, substitute
materials or supplies of an equivalent quality may be used with the approval of
Tenant (which shall not be unreasonably withheld); (ii) shall comply with all
licenses and permits issued with respect to the construction; and (iii) will not
violate any applicable law or regulation and will conform to all zoning and
environmental restrictions or any variances granted with respect thereto. The
Landlord agrees that it shall provide exterior landscaping of the Premises, hard

<PAGE>

surface roadway, truck ramps and sewer and utility connections to the Addition
of a type and quality consistent with the Addition.

     (b) The Specifications provide that the interior of the Addition will have
finished perimeter walls, ceiling tiles, carpeting, bathroom facilities and
normal lighting and electrical outlet service (hereinafter the "Basic Finish
Work"). Landlord agrees to allow Tenant to make modifications in the Basic
Finish Work to the extent that such modifications will not cause an increase in
the aggregate cost of the Basic Finish Work (hereinafter the "Finish
Allowance"). Tenant agrees to use its best efforts to specify any such
modifications with reasonable advance notice so as to enable efficient use of
contracting resources. In the event that Tenant desires to make modifications
the cost of which will exceed the Finish Allowance, Landlord agrees to make such
modifications and Tenant agrees to bear the cost of such modifications to the
extent they exceed the Finish Allowance. Landlord and Tenant agree to cooperate
in design and performance of finish work for the Addition and to use their best
efforts to coordinate their respective activities to achieve efficiency and to
eliminate duplication of effort.

     (c) In the event that Tenant is unable to begin occupancy of the Premises
on December 1, 1985 because the construction of the Addition has not been
substantially completed in its entirety or because Landlord is unable to deliver
possession of the entire Premises for any other reason, then the Commencement
Date and thus the commencement of the lease term and of Tenant's obligation to
pay rent and to fulfill its other obligations hereunder shall be delayed until
such time as the construction of the Addition has been completed and the
Landlord is able to deliver possession of the Premises. The delay of the
Commencement Date as herein provided shall in no way impair the effectiveness or
continuance of this Lease Agreement and Landlord shall not be liable to Tenant
or to any third party for any damages or losses resulting from such delay.
Acceptance of possession of the Premises by Tenant shall be deemed to be
acceptance of the Building and the Addition in their condition at the time
thereof and acknowledgement that the Addition complies with the provisions of
Section 3(a).

     4.  Rent. For the use and occupancy of the Premises Tenant hereby covenants
         ----
and agrees to pay to or for the account of Landlord as rental ("Rental), without
deduction or offset, the following amounts:

     (a) An annual fixed rental calculated at the rate of $8.50 per square foot
of the Building and the Addition, being One Million Two Hundred Twenty-Five
Thousand Nine Hundred Fifty-Five and No/100 Dollars ($1,225,955.00) per year
(hereinafter the "Base Rental"), due and payable in advance in monthly
installments of One Hundred Two Thousand One Hundred Sixty Two and 92/100
Dollars ($102,162.92) at Landlord's business premises located at Patriots Park,
Bedford, Massachusetts, on the first

                                       2

<PAGE>

day of each and every calendar month during the term of this Lease Agreement; a
prorated and proportional rent shall be due for any periods of less than a
calendar month at the commencement and expiration of the lease term, all without
set off or deduction except as may be required by law in order to preserve any
claim of Tenant thereto.

     (b) All real estate taxes, or taxes in the nature of real estate taxes, or
taxes assessed in lieu of or in addition thereto (except income taxes of
general application, inheritance, estate or like taxes) including special and
general assessments, however the same may be designated, levied or to be levied
by any taxing authority upon the Premises throughout the entire term of this
Lease Agreement; the same shall be paid by Tenant directly to such taxing
authority upon presentation of the tax bill by Landlord but in no event later
than fifteen (15) days prior to the last date upon which such taxes may be paid
without interest or penalty. If the first or last year of the term of this Lease
Agreement shall not be co-extensive with the tax year the amount of taxes
payable by Tenant hereunder for such years shall be prorated in proportion to
the period of effectiveness of the Lease Agreement during such years. Tax
receipts shall be furnished to Landlord by Tenant from time to time upon request
to show Tenant's compliance herewith on a current basis. If requested by any
first mortgagee of the Premises, Tenant agrees to instead make monthly deposits
to such mortgagee on account of such taxes in an amount reasonably estimated to
be sufficient to pay such taxes when they become due, provided that such
deposits are maintained in a separate account and any interest payable with
respect thereto shall be payable to Tenant.

     (c) All costs of electricity, gas, fuel, water and sewage assessed against
the Premises.

     (d) All other costs and expenses of every kind with respect to operation,
maintenance and repair of the Premises (excepting those undertaken by Landlord
pursuant to Section 8(d).

     5. Cost of Living Adjustment. In the event that as of any anniversary of
        -------------------------
the Commencement Date (an "Anniversary Date") there shall have been an increase
in the CPI over the last Anniversary Date, the fixed rental payable pursuant to
Section 4(a) for the succeeding year shall be subject to adjustment as herein
provided. The amount of such adjusted fixed rental shall be equal to the sum of:
(i) the Base Rental; plus (ii) the Base Rental multiplied time the Adjustment
Percentage. In no event shall the adjusted fixed rental calculated hereunder be
less than the rental payable during the preceding year. As used herein: the
term "Base Rental" shall mean an annual rental of $1,225,955; the term "CPI"
shall mean the Consumer Price Index for Urban Wage Earners and Clerical Workers
for Boston, Published by the United States Department of Labor, Bureau of Labor
Statistics, using 1967 as base 100 (or any other index which supercedes such
index); the term "Adjustment Percentage" shall mean the

                                       3

<PAGE>

percentage derived from a ratio having as its denominator Y and as its numerator
the difference between X and Y where X is the monthly index number last
established under the CPI prior to the Anniversary Date in question and Y is the
monthly index number last established under the CPI prior to the Commencement
Date.

     6.   Net Lease. It is the intention of the parties hereto that this is a
          ---------
net lease and that all costs of ownership, maintenance and use of the Premises
shall be paid by Tenant in addition to the fixed rent specified above and other
sums payable by Tenant hereunder (each of which shall be treated as Rental, for
non-payment of which Landlord shall have all rights which Landlord would have
for non-payment of fixed rent hereunder), provided, however, that Landlord
                                          --------  -------
shall be responsible for maintenance and repair of structural portions of the
Building and the Addition in accordance with Section 8(d) hereof. Tenant shall
pay to or on behalf of Landlord, through the term of this Lease Agreement, the
rent and other payments hereunder, free of any charges, assessments, impositions
or deductions of any kind, all of which Tenant shall pay or discharge, without
abatement, deduction or set off, and Landlord shall not be required to make any
payment of any kind whatsoever hereunder (whether due to circumstances now
existing or beyond present contemplation of the parties), except as herein
otherwise set forth. The rights of the parties in the event of a casualty to the
Premises shall be governed by Section 15 hereto.

     7.   Tenant's Covenants. Tenant further covenants and agrees as follows:
          ------------------

     (a)  To maintain the Premises including the doors and windows thereof in
good repair, condition and order in accordance with good maintenance practices;
and to yield peaceable possession to Landlord of the Premises at termination or
expiration of this Lease Agreement free of all tenants and occupants in as good
repair and condition as at occupancy by Tenant or may be put thereafter except
for ordinary wear and tear, obsolescence, and damage caused by fire (unless
caused by Tenant's negligence or default and not insured against or required to
be insured against hereunder) or the elements.

     (b)  To comply fully with any applicable statutes, ordinances, and lawful
regulations, rules or orders pertaining to the Premises and to the activities
conducted thereon, to comply with all applicable rules or conditions reasonably
imposed with respect to the Premises by any insurance carrier, and to prevent
the existence of any nuisance, or the violation of any statute, ordinance or
valid rule, order or regulation with respect thereto and to save Landlord
harmless from any failure to do so.

     (c)  To keep the Building and the Addition insured to the extent of
building replacement costs, against loss or damage by fire, windstorm, hail,
explosion and the other risks included in extended coverage policies from time
to time, subject, however to

                                       4
<PAGE>

a "deductible" clause in the amount of $50,000 or such other amount as Tenant
shall reasonably request and Landlord shall approve, which approval shall not be
unreasonably withheld or delayed; all of such policies shall name as insured
Landlord, any first mortgagee of the Premises and Tenant, as their respective
interests may appear and shall provide that they may not be cancelled without at
least fifteen (15) days' prior written notice to Landlord (provided, that such
additional notice does not result in the imposition of additional premiums or
charges by such insurer).  Tenant agrees to furnish Landlord with a
certificate by the insurer as to the existence thereof, together with a copy of
such policy.  Tenant may procure such insurance under a so-called blanket policy
insuring other locations of the Tenant, provided however, that such policy shall
provide on its face that such portion of the face amount as is required by this
Lease Agreement is payable with respect to covered loss relating to the Premises
and is not affected by losses on other premises.

     (d)  To the fullest extent permitted by law, to indemnify Landlord fully
against and to save Landlord harmless from loss, liability, costs, expense,
attorney's fees and court costs, arising directly or indirectly from any claim
or lawsuit by any person, firm, corporation, association or governmental agency
or authority whomsoever, including (but not limited to) Tenant's officers,
agents, employees or invitees, for damages assertedly sustained to person or
property by reason of any activity conducted by Tenant upon the Premises, or of
any breach by Tenant, its officers, agents, employees, or invitees of the terms,
provisions and conditions of this Lease Agreement, or occurring upon the
Premises or areas controlled by the Tenant by reason of the conduct of the
Tenant, its officers, agents, employees and invitees, regardless of the merit or
lack of merit of any such claim or lawsuit, of the fault or lack of fault on the
part of Landlord and regardless of the amount of insurance carried; and further,
to procure and keep in force, at Tenant's sole expense, public liability
insurance covering the Premises, with minimum limits of at least $5,000,000.00
for the death of or bodily injury to any one person, and $5,000,000.00 for the
death of or bodily injury to any number of persons resulting from the same
event, and of $1,250,000.00 for property damage naming Landlord, any first
mortgagee of the Premises and Tenant as insureds, as their respective interests
may appear, provided that if greater coverage limits are normally carried under
similar circumstances, Tenant agrees to increase such coverage limits
appropriately.

     (e)  To use its best efforts to prevent the filing or imposition of any
lien of any kind whatsoever upon or against the Premises based upon or arising
out of Tenant's actions, except by Landlord or with Landlord's prior written
consent and in the event of the filing or imposition of any such lien, to
discharge same or to obtain a surety bond sufficient to discharge same within 30
days following the date of any such filing or imposition.

                                       5

<PAGE>

     (f) To permit Landlord to enter the Premises during normal business hours
and, subject to Tenants's reasonable security and confidentiality requirements,
where such entry will not unreasonably disturb or interfere with Tenant's use of
the Premises and the operation of Tenant's business, to examine, inspect,
provide services or make repairs, replacements, changes or alterations as set
out in this Lease Agreement, and to take such steps as Landlord may reasonably
deem necessary for the safety, improvement or preservation of the Premises.
Landlord shall give reasonable notice to Tenant prior to any such entry, except
in the case of an emergency, but no such entry shall constitute an eviction or
entitle Tenant to any abatement of Rental.

     (g) In the event that Tenant shall fail to perform any act required by the
foregoing covenants and such failure shall continue for a period of 30 days
after notice thereof from Landlord, Landlord may (but shall not be obligated to
do so) perform such act without waiving or releasing Tenant from any of its
obligations with respect thereto.  Except for the performance of an act required
of Tenant's subleasee, Spire Corporation, Landlord shall be entitled to recover
from Tenant all sums paid or costs incurred in performing such acts on demand.

     8.  Landlord's Covenants. The Landlord hereby represents, warrants,
         --------------------
covenants and agrees as follows:

     (a) That Landlord has good and marketable title to the Premises, free and
clear of all liens and encumbrances; as of the date hereof, title to the
Premises is adequately insured with a reputable title insurance company under a
policy in form and amount acceptable to Tenant and Landlord has full right and
authority to lease the Premises and to carry out its obligation under this Lease
Agreement.

     (b) To the best of Landlord's knowledge, the Premises may be used for
warehouse, office, research and development and manufacturing purposes under all
applicable zoning, wetlands, conservation and other ordinances and regulations;
Landlord knows of no reason why an occupancy permit will not be issued with
respect to Tenant's use of the Building and the Addition.

     (c) To agree to release Spire Corporation from its obligations under a
lease agreement, dated February 1, 1983, as amended by instrument, dated
September 20, 1983, as of the Commencement Date so that Spire Corporation shall
be free to enter into the sublease contemplated by Section 9 with Tenant.

     (d) To maintain all structural portions of the Premises including
foundations, roofs, exterior walls, structural members and other supporting
structures, in good repair, condition and order; provided, however, that
Landlord's responsibility for repair and maintenance of roofs shall exclude
responsibility for

                                       6
<PAGE>

repair of (i) leaks occurring by reason of roof penetrating structures installed
or constructed by Tenant after the Commencement Date; and (ii) isolated minor
leaks properly repaired by simple patching procedures (as opposed to a leak or
series of leaks which properly require replacement or restoration of all or any
portion of a roof), provided, further, that Landlord shall be obligated to make
any repairs required by reason of the negligence or default of Tenant, its
officers, agents, employees and invitees except to the extent that Landlord
shall be insured against the same and received the proceeds of such insurance
and Landlord's mortgagees shall not retain the proceeds of such insurance. To
install separate meters to measure usage of utility services for the space to be
occupied by Spire Corporation and for the balance of the Premises.

     (e) To give Tenant prompt notice of the name and mailing address of any
mortgagee or holder of a first mortgage lien with respect to the Premises and of
any change therein.

     9.  Subletting. Coincident with this Lease Agreement Tenant is entering
         ----------
into a sublease agreement with Spire Corporation, an affiliate of Landlord,
covering the Building and a portion of the Addition. In addition, subject to all
of the provisions of this Lease Agreement, all or any portion of the remaining
part of the Premises may be sublet by Tenant; but Tenant shall have no right to
assign this Lease Agreement nor any of its rights hereunder (other than
assignment to an entity controlling, controlled by or under common control with
Tenant or pursuant to the sale of the entire business and assets of the division
of Tenant occupying the Premises provided, however, that without the consent of
Landlord no such assignment shall relieve Tenant of liability hereunder), nor
may same be assigned or pass to another by operation of law, and any attempt to
so assign, without the express prior consent of Landlord, shall be utterly void.
Tenant agrees that it shall in no event sublease to a direct or indirect
competitor of Spire Corporation or to any other unsuitable or objectionable
party; Tenant further agrees to promptly provide Landlord with the name and
address of the sublessee and a description of the terms of the sublease
arrangement. Tenant shall, however, be entitled to retain any premium over the
Rental provided hereunder which it receives under any such sublease.

     10. Signs. Tenant shall be entitled to erect reasonable ground and building
         -----
signs, subject to approval of Landlord, which shall not be unreasonably
withheld. All signs installed by Tenant shall comply with all requirements of
appropriate governmental authorities, and all necessary permits or licenses
shall be obtained by Tenant. Tenant shall maintain all signs in good condition
and repair at all times, and shall save Landlord harmless form injury to person
or property, arising from the erection and maintenance of said signs. Upon
vacating the Premises, Tenant shall remove all signs and repair all damage
caused by such removal.

                                       7

<PAGE>

     11.  Alterations and Improvements by Tenant. (a) Tenant shall have the
          --------------------------------------
right during the continuance of this Lease Agreement to make such alterations,
changes and improvements to the Premises as may be proper and necessary for the
conduct of Tenant's business and for the full beneficial use of the Premises.
Tenant shall not make any structural change in the Premises without first having
obtained Landlord's written consent thereto, without limitation Landlord may
condition any such consent by reserving the right to require the Premises to be
restored to the same condition they were in prior to the making of any such
structural change. Tenant shall pay all cost and expenses of such alterations,
changes, and improvements, shall make the same in a good and workmanlike manner,
and in accordance with all applicable laws, codes, and building regulations, and
shall, prior to the making of such alterations, changes, and improvements,
assure Landlord, in form satisfactory to Landlord, that payment for the same
will be made by Tenant. Tenant hereby completely and fully indemnifies Landlord
against any Mechanic's Liens or other liens or claims in connection with the
making of such alterations, changes and improvements. Any liens arising out of
such alterations, changes, and improvements shall be discharged of record by
Tenant within thirty (30) days after the same have been filed. Tenant shall pay
any and all taxes relating to its personal property, business, or improvements
and alterations constructed as provided in this Section 11.

     (b)  Except as otherwise provided, all signs, furnishings, trade fixtures
and other removable equipment installed in the Premises by Tenant and paid for
by Tenant shall remain the property of Tenant and shall be removed by Tenant
upon the termination of this Lease Agreement provided that any of such as are
affixed to the Premises and require severance shall be removed at Tenant's cost,
and Tenant shall immediately repair any damage caused by such removal.

     12.  Waiver of Subrogation. Each of Landlord and Tenant hereby releases the
          ---------------------
other from any and all liability or responsibility to the other or anyone
claiming through or under them by way of subrogation or otherwise for any loss
or damage to property caused by fire or any other perils insured or required to
be insured against in policies of insurance covering such property, even if such
loss or damage shall have been caused by the fault or negligence of the other
party, or anyone for whom such party may be responsible, including any
sub-tenants or other occupants of the Premises; provided, however, that this
release shall be applicable and in force and effect only to the extent that such
release shall be lawful at that time and in any event only with respect to loss
or damage occurring during such times as the releasor's policies shall contain a
clause or endorsement to the effect that any such release shall not adversely
affect or impair said policies or prejudice the right of the releasor to recover
thereunder and then only to the extent of the insurance proceeds payable under
such policies. Each of Landlord and Tenant agrees that it will request its
insurance carriers to include in its

                                       8

<PAGE>

policies such a clause or endorsement.  If extra cost shall be charged therefor,
each party shall advise the other thereof and of the amount of the extra cost,
and the other party, at its election, may pay the same, but shall not be
obligated to do so.  If such other party fails to pay such extra cost, the
release provisions of this paragraph shall be inoperative against such other
party to the extent necessary to avoid invalidation of such releasor's
insurance.

     13.   Subordination.  (a)  Tenant, upon demand by Landlord, agrees to give
           -------------
a waiver of priority of Tenant's lien arising by virtue of the within leasehold
estate, thereby subordinating Tenant's lien in favor of any mortgage loan, any
mortgage lien, or any refinancing or replacing of a mortgage loan that Landlord
may determine necessary or desirable from time to time, which election may be
changed from time to time.  Tenant agrees to execute such instruments as may be
required by any such lending institution or prospective first mortgagee in order
to effectuate such waiver of priority and subordination of Tenant's lien and
such certificates as to the status of this Lease Agreement and other matters as
such mortgagees shall reasonably require. Tenant shall be bound by and observe
all conditions of said mortgage which shall require the giving of reports and
copies of notices to any such mortgagees, as well as those which afford such
mortgagees the opportunity to cure any default of Landlord hereunder and,
subject to paragraph (b) below, to take possession of the Premises without
liability for any default of the Landlord occurring prior thereto or which
cannot reasonably be cured by such mortgagee not be subject to any offset or
defenses on account thereof nor bound by any prepayment of rent beyond the then
current period. In the event any proceedings are brought for foreclosure, or in
the event of the exercise of the power of sale under any mortgage or deed of
trust, Tenant shall attorn to the purchaser in any such foreclosure or sale and
recognize such purchaser as landlord under this Lease Agreement.

     (b)   Upon the request of Tenant, Landlord shall procure from any such
lending institution or mortgagee an agreement in writing, which shall be
delivered to Tenant, providing in substance that so long as Tenant shall
faithfully discharge the obligations on its part to be kept and performed under
the terms of this Lease Agreement, Tenant's tenancy will not be disturbed nor
this Lease Agreement affected by any default under such mortgage, and Tenant
agrees that this Lease Agreement shall remain in full force and effect even
though default in the mortgage may occur.

     14.   Limitation of Landlord Liability.  (a)  If Landlord shall fail to
           --------------------------------
perform any covenant, term or condition of this Lease Agreement upon Landlord's
part to be performed and, as a consequence of such default, Tenant shall recover
a money judgment against Landlord, such judgement shall be satisfied only out of
the interest of Landlord in the Premises or mortgage proceeds therefrom and
Landlord shall not be liable for any deficiency. It is understood and agreed
that in no event shall Tenant have

                                       9

<PAGE>

any right to levy execution against any property of Landlord other than its
interest in the Premises as hereinbefore expressly provided. Upon receipt of
notice to do so from any first mortgagee of the Premises, Tenant agrees to give
written notice to such mortgagee in the event of any default hereunder by
Landlord. Nothing herein contained shall be deemed to in any way limit or
restrict Tenant's right to obtain specific performance or other injunctive or
equitable relief with respect to the performance by Landlord of its covenants
set forth in Sections 19 and 20 hereof.

     (b)  To the fullest extent permitted by law, Tenant hereby agrees that
Landlord shall not be liable for any claim for damage to person or property
sustained by Tenant or any person claiming through Tenant resulting from any
accident or occurrence in, about, or upon the Premises unless due to the fault
or negligence of Landlord and Landlord's failure to make such repairs as it is
obligated to make within a reasonable period after notice from Tenant of the
need for such repairs. Said waiver shall include claims for unforeseen acts or
events resulting in damage or injury to person or property sustained by Tenant
or any person claiming through Tenant.

     (c)  Subject to Landlord's compliance with its obligations under Sections
19 and 20, the sale, conveyance or assignment of the Premises shall operate to
release Landlord from liability, from and after the effective date thereof, upon
all of the covenants, terms and conditions of this Lease Agreement, express or
implied, except as such may relate to the period prior to such effective date,
and Tenant shall with respect to claims arising thereafter look solely to
Landlord's successor in interest in and to this Lease Agreement. This Lease
Agreement shall not be affected by any such sale, conveyance or assignment, and
Tenant shall attorn to Landlord's successor in interest thereunder.

     (d)  Landlord shall not be deemed to be in default of its obligations
under this Lease Agreement unless Landlord or any mortgagee of which Tenant has
been given notice pursuant to Section 8(e) shall have received notice thereof
and such default shall continue uncured for a period of thirty (30) days
following receipt of such notice. No performance by any such mortgagee of
Landlord's obligations or exercise of its rights, undertaken in a
commercially reasonable manner, shall subject such mortgage to any liability
under this Lease Agreement.

     15.  Casualty to Premises. (a) If, during the term hereof, the Premises
          --------------------
shall be destroyed or so damaged by fire or other casualty as to be unfit, in
whole or in part, for occupancy and such destruction or damage can reasonably
be repaired to substantially the same form and condition and with substantially
the same materials as before such destruction or damage, within nine (9) months
following the date thereof, then Tenant shall not be entitled to surrender
possession of the Premises nor shall

                                      10
<PAGE>

Tenant's liability to pay rent under this Lease Agreement cease without the
mutual consent of the parties hereto. In the event of any such destruction or
injury, Landlord shall repair the same with all reasonable speed and shall
complete such repairs within nine (9) months from the date of such damage or
destruction. If during such period Tenant shall be deprived of the use of all or
any portion of the Premises, a proportionate allowance shall be made to Tenant
from the Rental corresponding to the time during which and to the portion of the
Premises of which Tenant shall be so deprived.

     (b)  If such destruction or injury cannot reasonably be repaired to such
former condition within nine (9) months from the date of such destruction or
damage, Landlord shall notify Tenant within sixty (60) days after the happening
of such destruction or damage whether or not Landlord will repair or rebuild. If
Landlord shall elect to repair or rebuild, Landlord shall specify the time
within which such repairs or reconstruction will be completed, and Tenant shall
have the option, exercisable within thirty (30) days after the receipt of such
notice, to elect either to terminate this Lease Agreement and any further
liability hereunder or to extend the term of the Lease Agreement (at the rental
in effect immediately preceding expiration of the normal term hereof) by a
period of time equivalent to the time from the happening of such destruction or
injury until the Premises are restored to such former condition. In the event
Tenant elects to extend the term of the Lease Agreement, Landlord shall restore
the Premises to such former condition within the time specified in such notice,
and Tenant shall not be liable to pay Rental for the period from the time of
such destruction or injury until the Premises are so restored to such former
condition.

     (c)  In the event that Landlord does not elect to repair or rebuild the
Premises pursuant to paragraph (b) above, then Tenant may at its option: (i)
terminate this Lease Agreement and any further liability hereunder; or (ii)
continue this Lease Agreement with the Rental adjusted to reflect the diminution
in the value of the Premises effected by such destruction or damage, effective
as of the date of such destruction or damage after such reconstruction. If
Tenant determines to continue this Lease Agreement pursuant to this paragraph
(c) then Tenant shall be entitled, at its cost and expense, to repair or
rebuild, in which event the purchase price for the Premises payable pursuant to
the right of first refusal granted by Section 19 hereof and the option to
purchase granted by Section 20 hereof, shall be adjusted to give Tenant
appropriate credit for the value added by the repair or reconstruction performed
by Tenant. Reconstruction shall be at least equal in quality to the original
construction of the building and shall, to the extent practical, be wholly
consistent in design and materials therewith. It shall be undertaken only in
full compliance with law after all permits and approvals have been obtained. It
shall be further undertaken only after plans and specifications therefor have
been approved

                                      11
<PAGE>

by Landlord, which approval shall not be unreasonably withheld or delayed.

     (d)  In the event of any such destruction or damage, Tenant shall be
entitled to reduction or abatement of Rental only as provided in this Section
15; Tenant shall not be entitled to any reduction or abatement in Rental
hereunder if any such damage or destruction is caused by an act or omission of
Tenant, its officers, agents, employees or invitees except to the extent that
Landlord shall be insured against same and receive to the proceeds of such
insurance.  Landlord shall have no liability to Tenant by reason of any injury
to or interference with Tenant's business or property arising from any such
destruction or damage unless caused by an act or omission of Landlord.
Landlord shall in no event be liable for any such injury or interference
resulting from the making of any repairs to the Premises undertaken by Landlord
in good faith.

     16.  Condemnation.  (a) In the event that the entire Premises shall be
          ------------
taken by condemnation or right of eminent domain, this Lease Agreement shall
terminate as of the day possession shall be taken by the taking authority,
and Landlord and Tenant shall be released from any further liability hereunder
thereafter accruing.

     (b)  In the event that only a portion of the  Premises shall be taken by
condemnation or right of eminent domain and the portion so taken renders the
balance unsuitable for the purpose of this Lease Agreement, the Tenant may, its
option, elect to terminate this Lease Agreement effective as of the day
possession shall be taken, provided thirty (30) days notice of such termination
is given.  If, in such case, this Lease Agreement is not terminated, Landlord
may, at its option restore the Premises with reasonable speed to an
architectural unit as nearly like its condition prior to such taking as shall be
practicable, and if during and/or after the work of restoration, Tenant is
deprived of  the use of all or a part of the Premises, an appropriate reduction
of Rental, depending upon the time during which and the portion of said
Premises of which Tenant is so deprived, shall be granted.  In the event
Landlord elects not to so restore the Premises, then Tenant may at its option:
(i) terminate this lease Agreement and any further liability hereunder; or (ii)
continue this Lease Agreement with the Rental adjusted to appropriately reflect
the diminution in value of the premises effected by such taking, effective as of
the date thereof. If Tenant elects to continue this Lease Agreement then Tenant
may, at its own cost and expense, so restore the Premises, in which event the
purchase price for the Premises payable pursuant to the right of first refusal
granted by Section 19 hereof and the option to purchase granted by Section 20
hereof shall be adjusted to give Tenant appropriate credit for the value added
to the Premises by the

                                      12

<PAGE>

restoration performed by Tenant and to reflect the diminution in value effected
by such taking.

     (c)  All damages awarded in connection with the taking of the Premises,
whether allowed as compensation for diminution in value to the leasehold or to
the fee of the Premises, shall belong to the Landlord. Notwithstanding the
foregoing, Tenant shall be entitled to make a separate claim for damage to
merchandise and movable trade fixtures, and removal, re-installation, and moving
expenses, provided it does not reduce the award payable to Landlord.

     17.  Default.  (a) If: (i) there be default in payment of any Rental which
          -------
shall continue for a period of ten (10) days following receipt by Tenant of
notice thereof from Landlord; or (ii) there shall be default in any other of
Tenant's obligations hereunder or if the Premises be abandoned or vacated by
Tenant, and if such default or condition shall continue for a period of thirty
(30) days following receipt by Tenant of notice from Landlord to make good such
default or correct such condition; or (iii) any proceedings under the present or
any future Bankruptcy Act be instituted by or against Tenant, or any receiver or
trustee be appointed for or ordered to dispose of Tenant's business or property,
or if Tenant makes any assignment or conveyance for benefit of creditors and if
any such proceeding instituted against Tenant shall not be dismissed within 20
days following the date of such institution; then, in such event Landlord shall
have the right, immediately or at any time thereafter, to enter upon the
Premises in the name of the whole and repossess the same as of its former estate
and expel Tenant and all those claiming by, through or under it, and remove
their goods and effects (forcibly if necessary) and store the same of behalf of
Tenant without being deemed guilty of any manner of trespass and without
prejudice to any remedies which might otherwise be used for arrears of rent or
other default hereunder and upon entry as aforesaid this Lease Agreement shall
be terminated. Landlord, at its election, may effect such termination by written
notice to Tenant to that effect, which shall have the same force as an entry for
breach as provided in this Section. In case of such termination, Landlord shall
become entitled to receive from Tenant, and Tenant shall pay to Landlord on
demand, as initial liquidated damages, a sum equal to the amount by which the
sum of the rent and other payments called for hereunder for the remainder of the
term exceeds the fair rental value of he Premises for the remainder of the term.
Further, Tenant shall, on demand of Landlord, from time to time indemnify
Landlord against all loss of rent, other payments and damages, however caused,
which it may incur by reason of such termination during the remainder of the
term, first giving credit to any payments made by Tenant to Landlord on account
of initial liquidated damages as aforesaid. In computing such damages there
shall be added such reasonable expenses as Landlord may incur in connection with
such termination and/or reletting, such as legal expenses, brokerage, expenses
for keeping the Premises in good

                                      13
<PAGE>

order and for preparing the same for reletting and expenses and/or decorations
in the Premises as may be necessary for the purpose of reletting. Landlord shall
also have the right to pursue such other rights and remedies as may be allowed
at law or equity against Tenant, and any and all other parties who may be
liable. All such remedies shall be cumulative. Provided, however, if any such
default be under clause (ii) above and it would not take more than thirty (30)
days to cure the same, Landlord shall not forfeit the lease created hereby,
enter upon the Premises or exercise any of the other remedies herein provided
for such default if Tenant begins the cure thereof within such period and
pursues same with reasonable due diligence to completion.

     (b) It is recognized that the primary sublessee of a portion of the
Premises shall be Spire Corporation, an affiliate of Landlord under a sublease
agreement of even date containing substantially identical covenants by Spire as
sublessee as those assumed hereunder by Tenant. Accordingly, in the event of a
breach of any covenant or other default hereunder by Tenant to the extent that
the act or omission giving rise to such breach or default arises out of a breach
or default under the sublease by Spire Corporation at a time when any Trustee or
beneficiary of Landlord is an officer, director or the direct or indirect holder
of more than 5% of the outstanding voting shares of said Spire Corporation
(hereinafter "Affiliated") then the provisions of this Section 17(b) shall
govern the rights of the parties with respect to such default. (1) The grace
periods specified in Section 17(a)(i) with respect to a default in payment of
rent shall be extended to forty-five (45) days following receipt of notice; and
the grace period specified in Section 17(a)(ii) and (iii) for default in any
other of Tenant's obligations shall be extended to one hundred and twenty (120)
days following receipt of notice. (2) In the event of any such default
continuing uncured beyond the applicable foregoing grace period, then the
Landlord shall be entitled, in lieu of the remedies provided in Section 17(a),
to exercise the following remedies: To declare this Lease Agreement terminated
with respect only to the portion of the Premises occupied by Spire Corporation
(the "Spire Space") and enter upon and repossess the Spire Space free of the
lease created hereby; or Landlord may, at Landlord's option, enter upon and
repossess the Spire Space, as aforesaid, and, as agent of Tenant, relet the same
for the balance of the term of this Lease Agreement, or for a shorter or a
longer term, and may receive the rents therefor, applying the same, first to the
payment of the expense of such reletting (including legal and brokerage fees and
cost of preparing the Premises for releasing) and then to the payment of rent
due and to become due under this Lease Agreement, Tenant remaining liable for an
agreeing hereby to pay Landlord any deficiency. Provided, however, if any such
default be other than for nonpayment of money and it would take more than one
hundred twenty (120) days to cure the same, Landlord shall not forfeit the lease
created hereby or enter upon the Spire Space for such default if Tenant begins
the cure thereof within such

                                      14

<PAGE>

period and pursues same with reasonable due diligence to completion.

     (c)  In the event that Tenant shall be in default under the provisions of
Section 17(a) by reason of a breach or default by Spire Corporation of its
obligations under its sublease with Tenant at a time when Spire Corporation is
not Affiliated with Landlord, then the provisions of this Section 17(c) shall
---
govern the rights of the parties with respect to such default. (1) The grace
periods specified in Section 17(a)(i) with respect to a default in payment of
rent shall be extended to thirty (30) days following receipt of notice; and the
grace period specified in Section 17(a)(ii) and (iii) for default in any other
of Tenant's obligations shall be extended to ninety (90) days following receipt
of notice. (2) In the event of any such default continuing uncured beyond the
applicable foregoing grace period, then the Landlord shall be entitled, in lieu
of the remedies provided in Section 17(a), to exercise the following remedies:
To declare this Lease Agreement terminated with respect only to the portion of
the Premises occupied by Spire Corporation (the "Spire Space") and enter upon
and repossess the Spire Space free of the lease created hereby; or Landlord may,
at Landlord's option enter upon and repossess the Spire Space, as aforesaid,
and, as agent of Tenant, relet the same for the balance of the term of this
Lease Agreement, or for a shorter or a longer term, and may receive the rents
therefor, applying the same, first to the payment of the expense of such
reletting (including legal and brokerage fees and the cost of preparing the
Premises for releasing) and then to the payment of rent due and to become due
under this Lease Agreement, Tenant remaining liable for and agreeing hereby to
pay Landlord any deficiency. Provided, however, if any such default be other
than for nonpayment of money and it would take more than ninety (90) days to
cure the same, Landlord shall not forfeit the lease created hereby or enter upon
the Spire Space for such default if Tenant begins the cure thereof within such
period and pursues same with reasonable due diligence to completion.

     18.  Quiet Enjoyment.  The Landlord covenants and agrees with Tenant that
          ---------------
as long as the Tenant keeps and performs all of the covenants and conditions to
be performed by Tenant hereunder, during the term of this Lease Agreement Tenant
shall have quiet and undisturbed and continued possession of the Premises, free
from any claims against the Landlord and all persons claiming under, by or
through the Landlord.

     19.  Right of First Refusal to Purchase.  In the event that during the term
          ----------------------------------
of this Lease Agreement or any extension hereof, the Landlord elects to sell all
or any portion of the Premises or any interest therein, Tenant shall have the
right of first refusal to meet any bona fide offer of sale on the same terms and
conditions as such offer. The Landlord shall give Tenant notice of all of the
terms and conditions thereof and Tenant shall have thirty (30) days thereafter
to exercise its right of first

                                      15

<PAGE>

refusal. Tenant shall have a period of one year following its exercise of its
right of first refusal to consummate the purchase of the Premises (or the
portion thereof covered by any such offer) at the specified purchase price plus
interest calculated from the date of such exercise to the date of consummation
of the purchase. Interest hereunder shall be calculated at the 90 day U.S.
Treasury Bill rate in effect on the date Tenant exercises its right of first
refusal, less all amounts of Base Rental paid during such period. Should Tenant
elect not to exercise its right of first refusal hereunder, the Landlord shall
have sixty (60) days thereafter to consummate the sale to third parties upon
substantially identical terms and conditions specified in said notice. Any
variation of said terms and conditions shall require a re-submission of the
offer to Tenant under this right of first refusal. Tenant's failure to exercise
this right or its waiver thereof with respect to any proposed transaction shall
not constitute a waiver of the right of first refusal created herein with
respect to any subsequent transaction by the named Landlord.

      20.   Option to Purchase. Landlord hereby grants Tenant the right and
            ------------------
option to purchase the Premises from the named Landlord in accordance with the
terms and conditions of this Section 20. The option to purchase granted
hereunder shall take effect June 1, 2005 and shall expire at midnight November
30, 2005. The option may be exercised at any time during such period by notice
to Landlord stating Tenant's intention to exercise such option, delivered or
mailed by certified mail, return receipt requested, to Landlord's address herein
provided. The purchase price for the Premises shall be fair market value at the
time of exercise computed as if the Premises were vacant and not subject to this
Lease Agreement. It Tenant and Landlord cannot agree on fair market value, it
shall be determined by a panel of three appraisers, one selected by Landlord,
one selected by Tenant and the third chosen by the two appraisers so selected.
Each such appraiser shall have at least ten years of experience in valuing
commercial property of the nature of the Premises. If the panel of appraisers
cannot agree on a fair market value for the Premises, the value shall be
established from the three fair market values placed upon the Premises in good
faith by each of the appraisers as follows: (i) if any individual value is
greater or less than the middle valuation by more than 20%, such valuation shall
be adjusted so that it is greater or less than such middle valuation by 20%; and
(ii) the fair market value shall be established by averaging the values after
any such adjustment. If the Tenant shall fail to exercise the option within the
period herein provided, it shall expire and be of no further effect.

      21.   Option to Sell.  Tenant hereby grants Landlord the right and option
            --------------
to sell the entire Premises to Tenant in accordance with the terms and
conditions of this Section 21.  The option to sell granted hereunder shall take
effect on the

                                      16

<PAGE>

Commencement Date and shall expire at midnight November 30, 2005. The option to
sell may be exercised at any time during such period by notice to Tenant stating
Landlord's intention to exercise such option, delivered or mailed by certified
mail, return receipt requested, to Tenant's address herein provided. Tenant
shall have a period of one year following receipt of notice from Landlord of its
exercise of such option to consummate the purchase of the Premises at the
purchase price provided herein plus interest calculated from the date of receipt
of such notice to the date of consumation of such purchase. Interest hereunder
shall be calculated at the 90 day U.S. Treasury Bill rate in effect on the date
Tenant receives notice of Landlord's exercise of its option hereunder less all
amounts of Base Rental paid during such period. The purchase price for the
Premises shall be ninety percent (90%) of fair market value at the time of
exercise, computed as if the Premises were vacant and not subject to this Lease
Agreement. If Tenant and Landlord cannot agree on fair market value, it shall be
determined by a panel of three appraisers, one selected by Landlord, one
selected by Tenant and the third chosen by the two appraisers so selected. Each
such appraiser shall have at least ten years of experience in valuing commercial
property of the nature of the Premises. If the panel of appraisers cannot agree
on a fair market value for the Premises, the value shall be established from the
three fair market values placed upon the Premises in good faith by each of the
appraisers as follows: (i) if an individual value is greater or less than the
middle valuation by more than 20%, such valuation shall be adjusted so that it
is greater or less than such middle valuation by 20%; and (ii) the fair market
value shall be established by averaging the values after any such adjustment. If
the Landlord shall fail to exercise the option within the period herein
provided, it shall be expire and be of no further effect.

     22.  Cooperation of Landlord. Landlord hereby agrees to cooperate with
           ----------------------
Tenants efforts to: (i) obtain permission from appropriate state and local
authorities to construct a roadway connecting Tenant's abutting property to the
Premises; (ii) obtain approvals for utility connections which Tenant or its
subleases may require; and (iii) erect and maintain adequate security fences and
structures around the Premises.

     23.  Arbitration. If any controversy shall arise relating to the provisions
          -----------
of this Lease Agreement or the tenancy or other rights created hereby, and such
dispute shall not be resolved by the parties within fifteen (15) days after
either party shall notify the other in writing of its desire to arbitrate the
dispute, then the dispute shall be settled by arbitration. Such arbitration
shall be conducted at Boston, Massachusetts, under the rules then obtaining of
the American Arbitration Association. There shall be a board of three
arbitrators, one appointed by the Landlord, one appointed by the Tenant and a
third selected by the two so named. The arbitrators shall have no power to add
to, sub-

                                      17
<PAGE>

tract from or modify any of the terms or conditions of this Lease Agreement. The
award of the arbitrators shall be final and binding and conclusive on the
parties, provided, however, that nothing herein contained shall limit Tenant's
         --------  -------
right to exercise the rights referred to in the last sentence of Section 14(a)
hereof.

     24.  General Provisions.  (a) Words of any gender used herein shall be
          ------------------
construed to include any other gender, and words in the singular number shall be
held to include the plural, unless the context otherwise requires, (b) the terms
and provisions of this Lease Agreement shall inure to the benefit of and be
binding upon the parties hereto and their respective successors, permitted
assigns and legal representatives; (c) the headings used herein are for
reference purposes only and do not affect the meaning or construction hereof;
(d) this Lease Agreement may not be altered or amended and no waiver of any of
the provisions hereof shall be effective except by an instrument in writing
signed by both parties hereto; (e) all notices, consents, waivers or demands
hereunder shall be in writing and shall be delivered or mailed by Registered or
Certified mail, postage paid, to the party to whom given at the address setforth
above or at such other address as such party may specify in accordance with this
clause; (f) if any provision of this Lease Agreement shall be held to be
invalid, illegal or unenforceable, the validity, legality and enforceability of
the remaining provisions of this Lease Agreement shall not in any way be
affected or impaired thereby; (g) this Lease Agreement shall be governed by and
construed in accordance with the laws of the Commonwealth of Massachusetts;
(h) each of the parties represents and warrants to the other that it has not
dealt with any broker or finder in connection with this Lease Agreement and
agrees to indemnify and hold the other harmless from and against any claims,
liabilities or losses (including attorney's fees) arising out of a breach of
this warranty; (i) Landlord and Tenant shall each have the right to contest in
good faith the validity or amount of any tax, assessment, license fee, excise
fee and other charge for which it is responsible under this Lease Agreement
provided that no contest by Tenant may be undertaken unless Tenant shall, upon
Landlord's request, deposit with Landlord adequate and sufficient security
against any loss or damage which may ensue or involve the reasonable
possibility of forfeiture, sale or disturbance of Landlord's interest in the
Premises and that upon the final determination of any contest by Tenant, Tenant
shall immediately pay and satisfy the amount found to be due, together with any
costs, penalties and interest.  (j) In any case where either party hereto is
required to do any act, other than the making of any payment of Rental, the time
for performance thereof shall be extended for a period equal to any delay caused
by or resulting from any act of God, war, civil commotion, fire, casualty,
labor difficulties, shortages of labor, materials or equipment, governmental
regulations or other causes beyond such party's reasonable control, to the
extent that the perfor-

                                      18
<PAGE>

mance of such obligation was actually prevented thereby.
(k) This instrument constitutes the entire agreement between the parties
relating to the subject matter hereof and supercedes all prior negotiations,
contracts or understandings; Tenant acknowledges that except for the
Specifications and the provisions of Section 8 hereof, it has not been induced
to enter into this Lease Agreement based on any representations made by
Landlord.

     EXECUTED as of the date first hereinabove stated.

SPI-TRUST                               MILLIPORE CORPORATION

By  /s/ Roger S. Little                 By /s/ Geoffrey Nunes
  -----------------------------           ---------------------------
  Roger Little, Trustee                   Sr Vice President

                                      19

<PAGE>

                         COMMONWEALTH OF MASSACHUSETTS

Middlesex, ss.

     On this 25/th/ day of November, 1985, before me personally appeared Roger
Little, to me known to the person who executed the foregoing instrument in
behalf of SPI-Trust, and acknowledged that he executed the same as the free act
and deed of said SPI-Trust.

                                        /s/ Peter W. Walcott
                                        ------------------------------
[Notarial Seal]                         Notary Public
                                        My Commission Expires: 7/30/87

                         COMMONWEALTH OF MASSACHUSETTS

Middlesex, ss.

     On this 25/th/ day of November, 1985, before me appeared Geoffrey Nunes,
who being duly sworn, did say that he is the Senior Vice President of Millipore
Corporation and that the seal affixed to said instrument is the corporate seal
of said corporation, and that said instrument was signed and sealed in behalf of
said corporation by authority of its board of directors, and said Geoffrey Nunes
acknowledged said instrument to be the free act and deed of said corporation.

                                        /s/ Peter W. Walcott
                                        ------------------------------
[Notarial Seal]                         Notary Public
                                        My Commission Expires 7/30/87

                                      20
<PAGE>

                                   EXHIBIT A
                          Description of the Premises

The Premises contain a total of 14.4 acres and is comprised of the following
parcels of land:

1.   That certain parcel of land on the Westerly side of Wiggins Avenue in
     Bedford, Middlesex County, Massachusetts, being shown as Parcels C & D on
     a plan entitled "Plan of Land in Bedford, Mass. Owned by Moore & MacLeod"
     drawn by Joseph W. Moore Inc., dated November 27, 1968, and recorded in the
     Middlesex South District Registry of Deeds in Book 11622, Page 408,
     containing together 6.27 acres.

     Being the Premises conveyed to SPI-Trust by deed of James M. Fiore, dated
     August 11, 1978, and recorded with said deeds in Book 13513, Page 256.

2.   That certain parcel of land on the westerly side of said Wiggins Avenue
     being shown as Parcel B on a plan entitled "Plan of Land in Bedford, Mass.
     owned by Moore & MacLeod" drawn by Joseph W. Moore, Inc., dated Oct. 21,
     1967, and recorded with Middlesex South District Registry of Deeds in Plan
     Book 11450 as Plan 109 and bounded and described as follows:

     NORTHWESTERLY by Wiggins Avenue, as shown on said plan, 179.08 feet;
     SOUTHEASTERLY by land of Griffith Realty Trust, as shown on said plan,
          608.30 feet;
     SOUTHWESTERLY by Parcel A, as shown on said plan, 408.95 feet;
     NORTHWESTERLY by Parcel A, as shown on said plan, 597.61 feet; and
     NORTHEASTERLY by Parcel A, as shown on said plan, 42.01 feet.

     Containing an area of 4.135 acres, according to said plan.

     Being the premises conveyed to SPI-Trust by deed of Edmund H. Carnevale,
     Charles A. Ziegler and David Chleck, dated April 30, 1976, and recorded
     with said Deeds in Book 12970, Page 629.

3.   That certain parcel of land on the Westerly side of said Wiggins Avenue,
     being shown as Parcel E on a plan entitled "Plan of Land in Bedford, Mass.
     Owned by Moore & MacLeod" drawn by Joseph W. Moore, Inc., dated November
     27, 1968, and recorded in the Middlesex South District Registry of Deeds in
     Book 11622, Page 408, containing 4.03 acres.

     Being the Premises conveyed to Roger G. Little, Trustee of SPI-Trust by
     deed of Saint John's Preparatory School, dated December 10, 1982 and
     recorded with said Deeds in Book 14818, Page 412.

                                      21

<PAGE>

                                   EXHIBIT B

    List of Plans, drawings and construction specifications constituting the
    Specifications.

                                                                      LAST
                                                                      REVISION
PLAN NAME                     PREPARED BY           PRINT #           DATE
---------                     -----------           -------           -----
SITE PLAN                     JOSEPH W. MOORE CO.                     10/15/85
SITE PLAN AMMEND.             JOSEPH W. MOORE CO.                      3/17/85
CAFETERIA & KITCHEN PLANS     LEONARD S. PHILLIPS   SKE-1               8/6/85
CONF. ROOM & LOBBY                      "           SKE-2             11/21/85
FIRE PROTECTION DETAIL & NOTES          "           A1-C               5/30/85
PART PLAN - FIRST FLOOR                 "           A-1                9/10/85
"           "                           "           A-2                9/11/85
"           SECOND FLOOR                "           A-3                4/30/85
"           "                           "           A-4                9/10/85
ROOF PLAN & DETAILS                     "           A-5                5/30/85
ELEVATIONS                              "           A-6                7/18/85
"                                       "           A-7                7/18/85
WALL SECTIONS                           "           A-8                7/18/85
SECTIONS & DETAIL                       "           A-9                7/18/85
DETAIL & GREENHOUSE ENTRY               "           A-10               5/30/85
WINDOW DETAILS & ELEVATION              "           A-11               7/18/85
ELEVATOR DETAILS                        "           A-12               5/30/85
METAL STAIR DETAILS                     "           A-13               7/18/85
STAIR SECTIONS & DETAIL                 "           A-14               7/18/85
1/4 TOILET PLAN & ELEVATIONS            "           A-15               9/10/85
ROOM FINISH SCHEDULE & DETAIL           "           A-16               9/10/85
DOOR SCHEDULE                           "           A-17               9/11/85
REFLECTED CEILING PLAN                  "           A-18               9/10/85
ELECTRICAL SITE PLAN                    "           E-1                 8/6/85
"          LIGHTING PLAN                "           E-2                 8/6/85
"          "                            "           E-3                8/28/85
"          "                            "           E-4                5/30/85
"          "                            "           E-5                5/30/85

                                      22
<PAGE>

                               EXHIBIT B (cont.)
                               -----------------

                                                                       LAST
                                                                       REVISION
PLAN NAME                       PREPAREDED BY            PRINT #       DATE
---------                       -------------            -------       ----
ELECTRICAL POWER PLAN                "                   E-6           8/6/85
"          "                         "                   E-7           8/28/85
"          "                         "                   E-8           8/6/85
"          "                         "                   E-9           5/30/85
ELECTRICAL DIAGRAMS & SCHEDULE       "                   E-10          8/6/85
FIRST FLOOR PLAN                     "                   E-11          4/30/85
SECOND FLOOR HVAC              SED ASSOCIATES            M-3           8/10/85
HVAC SCHEDULE & DETAIL               "                   M-5           8/10/85
FIRST FLOOR PLUMBING                 "                   P-1           7/26/85
"          "                         "                   P-2           7/26/85
SECOND FLOOR PLUMBING                "                   P-3           6/5/85
"          "                         "                   P-4           6/5/85
ISOMETRIC PIPING DIAGRAM             "                   P-5           4/3/85
CAFETERIA PLUMBING PLANS             "                   P-6           9/26/85
FIRST FLOOR PLAN               LEONARD S. PHILLIPS       A1-a          7/18/85
SECOND FLOOR PLAN                    "                   A1-b          9/11/85
FIRST FLOOR PLAN HVAC          SED ASSOCIATES            M-1          10/11/85
"          "                         "                   M-2          10/11/85
SECOND FLOOR HVAC                    "                   M-4          10/11/85
HVAC SCHEDULE & DETAILS        SED ASSOCIATES            M-5          10/11/85
                               EASTERN BAKERY SUPPLY     1062          4/30/85
SECOND FLOOR REFLECT. CEILING  LEONARD S. PHILLIPS       SK-24         9/11/85
LANDSCAPE PLAN - PAVING              "                   SK-L100       7/30/85
RENOVA. TO EXISTING BUILDING         "                   SK-100        5/30/85
EXHAUST CURB & VENDING DETAILS EASTERN BAKERY SUPPLY     SK-26         9/25/85
FOUNDATION & FIRST FLOOR PLAN  LEONARD S. PHILLIPS       S-1           5/30/85
"          "                         "                   S-2           5/30/85
CONCRETE SECTION & DETAILS           "                   S-3           5/30/85
CONCRETE DOCK SECTION                "                   S-4           1/11/85
SECOND FLOOR FRAMING PLAN            "                   S-5           2/14/85
"          "                         "                   S-6           2/14/85

                                      23
<PAGE>

                               EXHIBIT B (cont.)
                               ----------------
                                                                      LAST
                                                                      REVISION
PLAN NAME                             PREPAREDED BY    PRINT #        DATE
---------                             -------------    -------        ----

ROOF FRAMING PLAN                            "         S-7            2/14/85
"         "                                  "         S-8            1/30/85
STRUCTURAL STEEL SECTION                     "         S-9            1/11/85
MISC. STEEL FRAMING DETAILS                  "         S-10           5/15/85
ADDED SUPPORTS TO EXIST ROOF STRUCT.         "         S-11           5/13/85

                                      24
<PAGE>

                      FIRST AMENDMENT TO LEASE AGREEMENT

     Reference is made to a certain Lease Agreement (hereinafter the "Lease
Agreement") made and entered into as of the 25th day of November, 1985, by and
between Roger G. Little, Trustee of SPI-Trust, under a declaration of trust,
dated May 3, 1976, and recorded with Middlesex South District Registry of Deeds,
Book 12970, Page 625, having a mailing address at Patriots Park, Bedford,
Massachusetts 01730 (the "Landlord") and Millipore Corporation, a Massachusetts
Corporation, with an address at 80 Ashby Road, Bedford, Massachusetts 01730 (the
"Tenant").

     In consideration of the mutual promises and agreements herein contained
Landlord and Tenant hereby agree that the following Paragraph 25 shall be added
to the Lease Agreement as of the date first above written.

          25.   Hazardous Waste. Tenant agrees that it shall not dispose of
                ---------------
          hazardous waste, defined as such by any applicable law or ordinance,
          upon the Premises. Tenant further agrees that it shall indemnify,
          defend and hold Landlord harmless of and from any breach of this
          covenant provided, however, that notwithstanding the foregoing, Tenant
                   --------  -------
          shall not be responsible for any such hazardous waste disposed of upon
          the Premises prior to the date of Tenant's occupancy and Landlord
          agrees that Landlord shall indemnify, defend and hold harmless Tenant
          as aforesaid of and from any breach of this covenant. Tenant shall
          include this provision in any Sublease and the same shall be
          enforceable by and for the benefit of Landlord.

     In all other respects the Lease shall remain in full force and effect in
accordance with its terms.

                                SPI-TRUST

                                By:  /s/ Roger G. Little
                                ----------------------------------
                                Roger G. Little as Trustee
                                and not individually

                                MILLIPORE CORPORATION

                                By:  /s/ Geoffrey Nunes
                                -----------------------------------
                                Title    Sr. Vice President

<PAGE>

                         COMMONWEALTH OF MASSACHUSETTS

Middlesex, ss.

     On this 5th day of December   , 1985, before me personally appeared
Roger G. Little, to me known to be the person who executed the foregoing
instrument in behalf of SPI-Trust, and acknowledged that he executed the same as
the free act and deed of said SPI-Trust.

                                             /s/ Peter W. Walcott
                                             -------------------------------
[Notarial Seal]                              Notary Public
                                             My Commission Expires: 7/30/87

                         COMMONWEALTH OF MASSACHUSETTS

Middlesex, ss.

     On this 5th day of December  , 1985, before me appeared Geoffrey Nunes, who
being duly sworn, did say that he is the Senior Vice President of Millipore
Corporation and that the seal affixed to said instrument is the corporate seal
of said corporation, and that said instrument was signed and sealed in behalf of
said corporation by authority of its board of directors, and said Geoffrey Nunes
acknowledged said instrument to be the free act and deed of said corporation.

                                             /s/ Peter W. Walcott
                                             -------------------------------
[Notarial Seal]                              Notary Public
                                             My Commission Expires: 7/30/87<PAGE>
                                                                    EXHIBIT 10.6

                          COMMERCIAL LEASE AGREEMENT

                                    BETWEEN

                             EBP 3, LTD., Landlord

                                      AND

                         MILLIPORE CORPORATION, Tenant
<PAGE>

                               TABLE OF CONTENTS
                               -----------------

<TABLE>
<CAPTION>
                                                                             Page No.
                                                                             --------
<S>                                                                          <C>
1.   PREMISES, TERM, AND BUILDING SHELL....................................        1
2.   BASE RENT, SECURITY DEPOSIT AND ADDITIONAL RENT.......................        2
3.   TAXES.................................................................        4
4.   LANDLORD'S MAINTENANCE................................................        5
5.   TENANT'S MAINTENANCE AND REPAIR OBLIGATIONS...........................        5
6.   ALTERATIONS...........................................................        6
7.   SIGNS.................................................................        7
8.   UTILITIES.............................................................        7
9.   INSURANCE; SELF-INSURANCE.............................................        7
10.  CASUALTY DAMAGE.......................................................        9
11.  LIABILITY, INDEMNIFICATION, WAIVER OF SUBROGATION AND NEGLIGENCE......        9
12.  USE...................................................................       10
13.  INSPECTION............................................................       11
14.  ASSIGNMENT AND SUBLETTING.............................................       11
15.  CONDEMNATION..........................................................       13
16.  SURRENDER OF PREMISES; HOLDING OVER...................................       13
17.  QUIET ENJOYMENT.......................................................       14
18.  EVENTS OF DEFAULT.....................................................       14
19.  REMEDIES..............................................................       14
20.  LANDLORD'S DEFAULT....................................................       16
21.  MORTGAGES.............................................................       18
22.  ENCUMBRANCES..........................................................       18
23.  MISCELLANEOUS.........................................................       19
24.  NOTICES...............................................................       20
25.  HAZARDOUS WASTE.......................................................       21
26.  LANDLORD'S LIEN.......................................................       22
27.  TENANT'S CANCELLATION RIGHT...........................................       22
28.  SECURITY SERVICE......................................................       23
29.  TENANT'S OPERATIONAL AREAS............................................       23
30.  LANDLORD'S BANKRUPTCY.................................................       24
31.  CONSENT...............................................................       24
32.  COUNTERPARTS; FACSIMILE SIGNATURES....................................       24
33.  EMERGENCY REPAIRS BY TENANT...........................................       24
</TABLE>

                                       i

<PAGE>

                             LIST OF DEFINED TERMS

<TABLE>
<CAPTION>
                                                                        Page No.
<S>                                                                     <C>
AAA..................................................................         17
affiliate............................................................         19
Arbitration Notice...................................................         17
Base Rent............................................................          2
Building.............................................................          1
Building.............................................................        B-1
Building Shell.......................................................          1
Building's Structure.................................................          5
Cancellation Fee.....................................................         22
Claimant.............................................................         16
Commencement Date....................................................          1
Consenting Party.....................................................         24
Damage Estimate......................................................          9
Delinquent Payment Date..............................................          3
Disabilities Acts....................................................        B-1
Election Notice......................................................        C-1
Environmental Law....................................................         21
Event of Default.....................................................         14
Fair Market Rental Rate..............................................        C-2
GAAP.................................................................          8
Hazardous Substances.................................................         21
HVAC System..........................................................          5
Improvements.........................................................        B-1
including............................................................         19
Indemnified Parties..................................................          9
Land.................................................................          1
Landlord.............................................................          1
Landlord Hazardous Substances........................................         22
Landlord's Assessment................................................        C-1
Landlord's Mortgagee.................................................         18
Law..................................................................         19
Laws.................................................................         19
Lease................................................................          1
Leasing Costs........................................................         22
Loss.................................................................         10
Mortgage.............................................................         18
MSDS.................................................................         21
Objection Notice.....................................................        C-1
Operating Expenses...................................................          2
Permitted Activities.................................................         21
Permitted Materials..................................................         21
Permitted Transfer...................................................         12
</TABLE>

                                      ii
<PAGE>

<TABLE>
<S>                                                                 <C>
Permitted Transferee.............................................    12
Premises.........................................................     1
Primary Lease....................................................    18
rent.............................................................     4
Repair Period....................................................     9
Security Deposit.................................................     2
Substantial Completion...........................................   B-1
Taking...........................................................    13
Tangible net worth...............................................     8
Target Date......................................................   B-1
Taxes............................................................     4
Tenant...........................................................     1
Tenant Party.....................................................    19
Tenant's Optional Areas..........................................    23
Term.............................................................     1
Termination Election Date........................................     2
Transfer.........................................................    11
Vacation Date....................................................    11
</TABLE>

                                      iii
<PAGE>

                                LEASE AGREEMENT
                                ---------------

     This Lease Agreement (this "Lease") is entered into by EBP 3, LTD., a Texas
                                 -----
limited partnership ("Landlord"), and MILLIPORE CORPORATION, a Massachusetts
                      --------
corporation ("Tenant").
              ------

     1.   PREMISES, TERM, AND BUILDING SHELL.
          ----------------------------------

          (a) Landlord leases to Tenant, and Tenant leases from Landlord, the
real property described on Exhibit A-l (the "Land"), which includes the
                           -----------       ----
approximately 178,013 square foot building depicted on Exhibit A-2 (the
                                                       -----------
"Building") being constructed on the Land, subject to the terms and conditions
 --------
in this Lease. The term "Premises" means the Land, Building, and related
                         --------
improvements.

          (b) The Lease term shall be 120 months (the "Term", which defined term
                                                       ----
shall include all renewals and extensions of the Term), beginning on the earlier
of (1) the date Tenant begins conducting business in the Premises and (2) June
1, 1998 (the "Commencement Date"); however, if Tenant is delayed in
              -----------------
substantially completing the interior improvements in the Building because the
shell of the Building (the "Building Shell") was not in a dried-in condition
                            --------------
sufficient to allow Tenant to begin its interior tenant improvement work on
February 1, 1998, then the Commencement Date will be delayed until the earlier
of: (A) June 1, 1998, plus the number of days obtained by performing the
following calculation:

          X - Y; where,

          X = the number of days after February 1, 1998, that the Building Shell
              was not in such a dried-in condition; and

          Y = the number of days of delay in achieving such a dried-in condition
              caused by a Tenant Party;

or (B) the date Tenant begins conducting business in the Premises. If the
Commencement Date is not the first day of a calendar month, then the Term shall
end on the last day of the 120-month period that begins on the first day of the
first full calendar month of the Term. Within ten days after either party's
requests therefor, Landlord and Tenant will execute an agreement setting forth
the Commencement Date.

          (c) Landlord shall construct the Building Shell in accordance with
Exhibit B. By occupying the Premises, Tenant shall have accepted the Premises in
---------
their condition, subject to completion of any unperformed items necessary to
complete the Building Shell as provided in Exhibit B. Notwithstanding anything
                                           ---------
in this Lease to the contrary, if the Building Shell is not substantially
completed by May 1, 1998, plus the number of days of delay in achieving
substantial completion caused by force majeure events described in Section
23.(c) and the number of days of delay in achieving substantial completion of
the Building Shell caused by a Tenant Party (the

                                       1
<PAGE>

"Termination Election Date"), then Tenant may terminate this Lease by delivering
 -------------------------
written notice thereof to Landlord before the earlier of the date the Building
Shell is substantially completed or ten days after the Termination Election
Date.

     2.   BASE RENT, SECURITY DEPOSIT AND ADDITIONAL RENT.
          -----------------------------------------------

          (a) Tenant shall pay to Landlord "Base Rent", in advance, without
                                            ---------
demand, deduction or set off (except as herein provided), equal to the following
amounts for the following periods of time:

          Time Period                   Monthly Base Rent
          -----------                   -----------------
          1 through 60                     $67,793.28
     61 through end of initial Term        $78,029.03

The first monthly installment of Base Rent shall be due on the date hereof;
thereafter, monthly installments of Base Rent shall be due on the first day of
each calendar month following the Commencement Date. If the Term begins on a day
other than the first day of a month or ends on a day other than the last day of
a month, the Base Rent and additional rent under Section 2.(c) for such partial
month shall be prorated.

          (b) Tenant shall deposit with Landlord on the date hereof $67,793.28
(the "Security Deposit"), which shall be held by Landlord to secure Tenant's
      ----------------
obligations under this Lease; however, the Security Deposit is not an advance
rental deposit or a measure of Landlord's damages for an Event of Default
(defined below). Landlord may use any portion of the Security Deposit to satisfy
Tenant's unperformed obligations hereunder, without prejudice to any of
Landlord's other remedies. If so used, Tenant shall pay Landlord an amount that
will restore the Security Deposit to its original amount upon request. In
connection with any waiver of a Tenant default or modification of this Lease,
Landlord may require that Tenant provide Landlord with an additional amount to
be held as part of the Security Deposit. The unused portion of the Security
Deposit plus 5% per annum thereon (compounded annually) will be returned to
Tenant within a reasonable time after the end of the Term (not to exceed 30
days), provided that Tenant has fully and timely performed its obligations
hereunder throughout the Term.

          (c) Tenant shall pay, as additional rent, all costs incurred in
operating, managing, and maintaining the Premises (collectively, "Operating
                                                                  ---------
Expenses"), including the following items: (1) Taxes (defined below); (2) the
--------
cost of insurance; (3) the cost of repairs and replacement of the items
described in Section 4.(b), management fees (which shall not exceed 3% of the
gross rent) and related out-of-pocket expenses of the manager, landscape
maintenance and replacement, security service (if provided), sewer service (if
provided), and trash service (if provided); (4) the cost of dues, assessments,
and other charges applicable to the Premises payable to any property or
community owner association under restrictive covenants or deed restrictions to
which the Premises are subject that affect all property subject thereto in a
similar manner; and (5) alterations, additions, and improvements relating to the
items described in Section 4.(b) made by Landlord to comply with Law (defined
below). Additional rent under this Section 2.(c) shall be payable by Tenant to
Landlord in monthly installments equal to 1/12 of Landlord's good faith estimate
of annual Operating Expenses. The initial monthly payments are based upon
Landlord's good faith estimate of the Operating,

                                       2
<PAGE>

Expenses for the year in question, and shall be increased or decreased annually
to reflect the projected actual Operating Expenses for that year.

          Within 90 days after each calendar year or as soon thereafter as is
reasonably practicable, Landlord shall deliver to Tenant a statement setting
forth the actual Operating Expenses for such year (an "Annual Operating Expense
                                                       ------------------------
Statement"). Each Annual Operating Expense Statement shall set forth a line item
---------
detail comparing the actual Operating Expenses for such calendar year to the
Operating Expenses for the preceding calendar year, the estimated payments paid
by Tenant toward Operating Expenses during the calendar year for which such
statement was prepared and an estimate of Tenant's obligation for Operating
Expenses for the next calendar year. If Tenant's total payments in respect of
Operating Expenses for any year are less than the Operating Expenses for that
year, Tenant shall pay the difference to Landlord within 30 days after
Landlord's request therefor; if such payments are more than the Operating
Expenses, Landlord shall pay to Tenant such excess within 30 days after Landlord
delivers to Tenant the applicable Annual Operating Expense Statement. Operating
Expenses shall not include the following: (A) any costs for interest,
amortization, or other payments on loans to Landlord; (B) federal income taxes
imposed on or measured by the income of Landlord from the operation of the
Premises; (C) rents under ground leases; (D) costs incurred in selling,
syndicating, financing, mortgaging, or hypothecating any of Landlord's interests
in the Premises; (E) costs incurred by Landlord to repair any damage to the
Building to the extent Landlord is reimbursed by insurance proceeds therefor;
(F) items which Landlord is obligated to perform under Section 4.(a); (G) costs
arising from latent defects in the Building Shell and other improvements
initially installed in the Premises pursuant to the Shell Plans; and (H) costs
incurred for services performed by an affiliate of either Landlord or its
building manager to the extent the cost thereof exceeds market rates for
comparable services. There shall be no duplication of costs for reimbursements
in calculating Operating Expenses. The amounts of the initial monthly Base Rent
and Operating Expenses (and the part thereof attributable to Taxes) are as
follows:

         Base Rent (Section 2.(a))..................................  $67,793.28
         Operating Expenses: excluding Taxes (Section 2.(c))........  $ 5,192.05
         Taxes (Sections 2.(c) and 3.(a))...........................  $10,384.09

         Total initial monthly payment..............................  $83,369.42

The first monthly installment of additional rent under this Section 2.(c) shall
be due on the date hereof; thereafter, monthly installments of such additional
rent shall be due on the first day of each calendar month following the
Commencement Date.

          (d) If any payment required of Tenant under this Lease for Base Rent
and Operating Expenses is not paid by the Delinquent Payment Date (defined
below), Landlord may charge Tenant a fee equal to 5% of the delinquent payment
to reimburse Landlord for its cost and inconvenience incurred as a consequence
of Tenant's delinquency. "Delinquent Payment Date" means, with respect to each
                          -----------------------
payment of Base Rent and Operating Expenses due from Tenant under this Lease,
the fifth day after Landlord delivers to Tenant written notice that the payment
in question has not been paid when due; however, if Landlord has previously
notified Tenant that Tenant has failed to pay rent when due twice during the
12-month period preceding the delinquent payment in

                                       3
<PAGE>

question, then the Delinquent Payment Date for that payment shall mean the day
after that payment was due.

          (e) All payments and reimbursements required to be made by Tenant
under this Lease shall constitute "rent" (herein so called) and shall be payable
                                   ----
without demand, deduction or set off (except as expressly set forth herein).

          (f) Inspection Right. After giving Landlord 30-days' prior written
              ----------------
notice thereof. Tenant may inspect or audit Landlord's records relating to
Operating Expenses for any periods of time within two years before the audit or
inspection; however, no audit or inspection shall extend to periods of time
before the Commencement Date. Tenant's audit or inspection shall be conducted
only during business hours reasonably designated by Landlord. Tenant shall pay
the cost of such audit or inspection, including a reasonable amount to reimburse
Landlord for its out-of-pocket costs allocable to the inspection or audit,
unless the total Operating Expenses charged to Tenant for the time period in
question is determined to be in error, and, as a result thereof, Tenant paid to
Landlord $3,000 more than the actual Operating Expenses due for such time
period, in which case Landlord shall pay the audit cost. Tenant may not conduct
an inspection or have an audit performed more than once during any calendar
year. If such inspection or audit reveals that an error was made in the
Operating Expenses previously charged to Tenant, then Landlord shall refund to
Tenant any overpayment of any such costs, or Tenant shall pay to Landlord any
underpayment of any such costs, as the case may be, within 30 days after
notification thereof. Tenant shall maintain the results of each such audit or
inspection confidential and shall not be permitted to use any third party to
perform such audit or inspection, other than an independent firm of certified
public accountants reasonably-acceptable to Landlord which agrees with Landlord
in writing to maintain the results of such audit or inspection confidential.

          (g) When calculating Operating Expenses, Landlord shall take into
account all abatements (including, without limitation, tax abatements),
exemptions, and discounts, such that Tenant shall only be obligated to pay the
actual Operating Expenses. Landlord shall cooperate with Tenant in obtaining tax
abatements, discounts, and exemptions, provided that Tenant reimburses Landlord
for all out-of-pocket costs incurred by Landlord in connection therewith.

     3.   TAXES.
          -----

          (a) Landlord shall pay all taxes, assessments and governmental charges
whether federal, state, county, or municipal and whether they are imposed by
taxing or management districts or authorities presently existing or hereafter
created (collectively, "Taxes") that accrue against the Premises. If, during the
                        -----
Term, there is levied, assessed or imposed on Landlord a capital levy or other
tax directly on the rent or a franchise tax, assessment, levy or charge measured
by or based, in whole or in part, upon rent, then all such taxes, assessments,
levies or charges, or the part thereof so measured or based, shall be included
within the term "Taxes".

          (b) Tenant shall (1) before delinquency pay all taxes levied or
assessed against any personal property, fixtures or alterations placed in the
Premises and (2) upon the request of Landlord, deliver to Landlord receipts from
the applicable taxing authority or other evidence acceptable to Landlord to
verify that such taxes have been paid. If any such taxes are levied or

                                       4
<PAGE>

assessed against Landlord or Landlord's property and (A) Landlord pays them or
(B) the assessed value of Landlord's property is increased thereby and Landlord
pays the increased taxes, then Tenant shall pay to Landlord such taxes within
ten days after Landlord's request therefor.

     4.   LANDLORD'S MAINTENANCE.
          ----------------------

          (a) This Lease is intended to be a net lease. Accordingly, Landlord's
maintenance obligations are limited to maintenance of the Building's roof,
foundation piers, structural slab, and structural members of the exterior walls
(collectively, the "Building's Structure"); painting of exterior walls; and
                    --------------------
caulking of tilt panels and windows; however, Landlord shall not be responsible
(1) for any such work until Tenant delivers to Landlord written notice of the
need therefor or (2) for alterations to the Building's Structure required by Law
because of Tenant's specific use of or particular activity (e.g., a specific
type of research and development) conducted in the Premises (which alterations
shall be performed by Tenant) as opposed to alterations required by Law in
general for office, warehouse, manufacturing and research and development use.
Landlord shall promptly make all such repairs after it has received notice of
the need therefor. The Building's Structure does not include windows (other than
caulking thereof) or components thereof (including flashing, etc.), glass or
plate glass: doors, special store fronts or office entries, all of which shall
be maintained by Tenant. Landlord's liability for any defects, repairs,
replacement or maintenance for which Landlord is responsible hereunder shall be
limited to the cost of performing such work.

          (b) Additionally, Landlord shall maintain the parking areas,
driveways, alleys and grounds surrounding the Premises in a clean and sanitary
condition, consistent with the operation of a first-class
office/warehouse/research/manufacturing building, including prompt maintenance,
repairs and replacements of (1) any drill or spur track servicing the Premises,
(2) the exterior portions of the Premises, (3) sprinkler systems and sewage
lines, and (4) any other items normally associated with the foregoing. All costs
incurred by Landlord in connection therewith (other than the painting of
exterior walls and caulking of tilt walls) shall be Operating Expenses.
Notwithstanding the foregoing, Landlord shall have no responsibility for
maintaining any portion of Tenant's Operational Areas (defined below), such
areas shall be under the sole dominion and control of Tenant.

     5.   TENANT'S MAINTENANCE AND REPAIR OBLIGATIONS.
          -------------------------------------------

          (a) Tenant shall maintain all parts of the Premises (except for
maintenance work which Landlord is expressly responsible for under Section
4.(a)) in good condition and promptly make all necessary repairs and
replacements to the Premises. Tenant shall repair and pay for any damage caused
by a Tenant Party (defined below), to the extent Landlord is not reimbursed
therefor by insurance proceeds.

          (b) Tenant shall maintain the hot water equipment and the heating, air
condition, and ventilation equipment and system (the "HVAC System") in good
                                                      -----------
repair and condition and in accordance with Law and with such equipment
manufacturers' suggested operation/maintenance service program; such obligation
shall include replacement of all equipment necessary to maintain such equipment
and system in good working order. At least 14 days before the end of the Term,
Tenant shall deliver to Landlord a certificate from an engineer reasonably
acceptable to Landlord

                                       5
<PAGE>

certifying that the hot water equipment and the HVAC System are then in good
repair and working order.

          (c) Tenant shall be responsible for all pest control in the Premises.

     6.   ALTERATIONS. Except as provided below, Tenant shall not make any
          -----------
alterations, additions or improvements to the Premises without the prior written
consent of Landlord which shall not be unreasonably withheld. Landlord may not
withhold its consent to any alteration, addition or improvement unless, in
Landlord's reasonable determination, the installation or use of such item would
violate Law, would cause the Premises or the use thereof to be in violation of
Law, would alter or adversely affect the Building's Structure, or would increase
Landlord's obligations under Section 4.(a) (unless Tenant agrees to pay all
additional costs incurred in connection therewith or as a result thereof).
Landlord shall not be required to notify Tenant of whether it consents to any
alteration, addition or improvements until it (a) has received plans and
specifications therefor which are sufficiently detailed to allow construction of
the work depicted thereon to be performed in a good and workmanlike manner, and
(b) has had a reasonable opportunity to review them (not to exceed ten business
days). If the alteration, addition or improvement will affect the Building's
Structure, HVAC System, life-safety, or mechanical, electrical, or plumbing,
systems, then the plans and specifications therefor must be prepared by a
licensed engineer reasonably acceptable to Landlord. Landlord's approval of any
plans and specifications shall not be a representation that the plans or the
work depicted thereon will comply with Law or be adequate for any purpose, but
shall merely be Landlord's consent to performance of the work. Upon completion
of any alteration, addition, or improvement, Tenant shall deliver to Landlord
accurate, reproducible as-built plans therefor. Unless Landlord specifies in
writing otherwise and except as provided in Section 16, all alterations,
additions, and improvements shall be Landlord's property when installed in the
Premises. All work performed by a Tenant Party in the Premises (including that
relating to the installations, repair, replacement, or removal of any item)
shall be performed in accordance with Law, in a good and workmanlike manner, and
so as not to damage the Building's Structure.

          Notwithstanding the foregoing, after the initial tenant improvements
have been installed by Tenant in the Premises and a certificate of occupancy has
been issued therefor, Tenant shall not be required to obtain Landlord's consent
for repainting, recarpeting, or other alterations totaling less than $50,000 in
any single instance or series of related alterations performed within a
six-month period, provided that such alterations do not alter or adversely
affect the Building's Structure. Tenant shall pay to Landlord or its designated
agent a construction management fee in connection with the design and
installation of the initial tenant improvements installed in the Premises by
Tenant equal to $25,000; such payment shall be made on or before the
Commencement Date. Tenant shall not be entitled to occupy the Premises unless
Tenant has obtained and delivered to Landlord a copy of the certificate of
occupancy therefor.

     7.   SIGNS. Provided that the maintenance thereof complies with all Laws,
          -----
and Tenant has received all approvals, consents, and permits required by Law
therefor, Tenant may install and maintain one monument sign on the Premises and
one sign on each of the two exterior facade panels placed on the Building by
Landlord. Landlord shall pay for the cost of placing the exterior facade panels
on the Building, and Tenant shall bear all other costs in connection with all
signs maintained at the Premises (including the cost of the signage to be placed
on the Building's sign panel). Each

                                       6
<PAGE>

sign's design, color scheme, location, material composition, and method of
installation must be approved by Landlord. Tenant shall maintain such signs in a
good, clean, and safe condition in accordance with all Laws. Tenant shall repair
all damage caused by the installation, use, maintenance, and removal of the
signs and, upon their removal, restore the Premises where such signs were
located to their condition immediately before the installation thereof (ordinary
wear and tear excepted, other than any discoloration caused thereby). Within ten
days after the earlier of (A) termination of Tenant's right to possess the
Premises or (B) the end of the Term, Tenant shall remove the signs and perform
all restoration work as provided above. If Tenant fails to do so within such
ten-day period, Landlord may, without compensation to Tenant, perform such work
and dispose of the signs in any manner it deems appropriate or deem such signs
abandoned and, after removing Tenant's logo therefrom, use such signs; Tenant
shall pay to Landlord all reasonable costs incurred in connection therewith
within 30 days after Landlord's request therefor.

     8.   UTILITIES. Tenant shall obtain and pay for all water, gas,
          ---------
electricity, heat, telephone, sewer, sprinkler charges and other utilities and
services used at the Premises, together with any taxes, penalties, surcharges,
maintenance charges, and the like pertaining to the Tenant's use of the
Premises. If Tenant fails to pay for such amounts, Landlord may do so, in which
case, Tenant shall reimburse Landlord therefor within ten days after Landlord's
request. Landlord shall not be liable for any interruption or failure of utility
service to the Premises.

          Notwithstanding the foregoing, if Tenant is prevented from making
reasonable use of the Premises for more than three consecutive days because of
the unavailability of any such service and such unavailability was primarily
caused by Landlord's negligence or willful misconduct, then Tenant shall be
entitled to a reasonable abatement of rent for each consecutive, day after the
expiration of such three-day period that Tenant is so prevented from making
reasonable use of the Premises.

     9.   INSURANCE; SELF-INSURANCE.
          -------------------------

          (a) Tenant shall maintain (1) workers' compensation insurance (with a
mutual waiver of subrogation endorsement reasonably acceptable to Landlord) and
commercial general liability insurance (with contractual liability endorsement),
including personal injury and property damage in the amount of $5,000,000 per
occurrence and (2) fire and extended coverage insurance covering (A) the
replacement cost of all alterations, additions, partitions and improvements
installed in the Premises, (B) the replacement cost of all of Tenant's personal
property in the Premises, and (C) loss of profits in the event of an insured
peril damaging the Premises. Such policies shall (i) name Landlord, Landlord's
agents, and their respective affiliates (defined below), as additional insureds
(and as loss payees on the fire and extended coverage insurance), (ii) be issued
by an insurance company acceptable to Landlord with a minimum AM Best rating of
A:X or better and licensed to do business in Texas, (iii) provide that such
insurance may not be cancelled unless 30-days' prior written notice is first
given to Landlord, (iv) be delivered to Landlord by Tenant before the
Commencement Date and at least 30 days before each renewal thereof (or
certificates thereof or other evidence thereof reasonably acceptable to Landlord
may be delivered), and (v) provide primary coverage to Landlord when any policy
issued to Landlord is similar or duplicate in coverage, in which case
Landlord's policy shall be excess over Tenant's policies.

                                       7
<PAGE>

          (b) Self-Insurance. Tenant may provide self-insurance in lieu of the
              --------------
insurance required in Section 9.(a)(2), whether by the establishment of an
insurance fund or reserve to be held and applied to make good losses from
casualties, or otherwise, which conforms to the practice of large corporations
maintaining systems of self-insurance. As a condition to establishing a
self-insurance plan in lieu of the insurance provided in Section 9. (a)(2),
Tenant shall deliver to Landlord the following: (1) a certificate of an
independent actuary or other independent, qualified person reasonably acceptable
to Landlord stating that the self-insurance plan is adequate to provide the
protection of the insurance policies described in Section 9.(a)(2) and (2) a
balance sheet as of the end of the most recent quarter of the then-current
fiscal year of Tenant (or, if the first quarter in such fiscal year has not
expired, the last quarter of the previous fiscal year), prepared by a national
firm of certified public accountants (reasonably acceptable to Landlord) in
accordance with generally accepted accounting principles consistently applied
("GAAP"), accompanied by such accounting firm's unqualified opinion that the
  ----
tangible net worth of Tenant exceeds $100,000,000. Thereafter, Tenant shall
deliver to Tenant as soon as available (and in any event within 45 days) after
the end of each fiscal year, a balance sheet for such fiscal year, prepared by a
national firm of certified public accountants (reasonably acceptable to
Landlord) in accordance with GAAP, accompanied by such accounting firm's
unqualified opinion that the tangible net worth of Tenant exceeds $100,000,000.
If any time Tenant's tangible net worth is less than $100,000,000, Tenant shall
be required to immediately obtain and maintain the insurance provided in Section
9.(a)(2). "Tangible net worth" means the excess of total assets over total
           ------------------
liabilities (in each case, determined in accordance with GAAP) excluding from
the determination of total assets all assets which would be classified as
intangible assets under GAAP, including limitation, goodwill, licenses, patents,
trademarks, trade names, copyrights, and franchises.

          (c) Casualty Insurance. Landlord shall maintain insurance insuring the
              ------------------
Building Shell against the perils included in the Special Causes of Loss form
including, but not limited to, fire, lightning, extended coverage, vandalism and
malicious mischief in an amount not less than 80% of the replacement cost
thereof. Landlord has the option, but not the obligation, to insure the Premises
for loss caused by earthquake or flood. Such insurance shall be for the sole
benefit of Landlord and under its sole control. Landlord shall not be obligated
to insure furniture, equipment, machinery, goods or supplies of Tenant which
Tenant may keep or maintain at the Premises or any leasehold improvements,
additions or alterations in the Premises.

     10.  CASUALTY DAMAGE.
          ---------------

          (a) Tenant immediately shall give written notice to Landlord of any
damage to the Premises. Within 30 days after Landlord has notice of the damage
in question, Landlord shall deliver to Tenant its good faith estimate of the
time necessary to complete Landlord's work with respect to the damage in
question (the "Damage Estimate"). If the Premises are totally destroyed by an
               ---------------
insured peril, or so damaged by an insured peril that, in Landlord's good faith
estimation, rebuilding or repairs cannot be substantially completed within nine
months after the date of Landlord's actual knowledge of such damage, then either
Landlord or (if a Tenant Party did not cause such damage) Tenant may terminate
this Lease by delivering to Landlord written notice thereof within 15 days after
Landlord delivers to Tenant the Damage Estimate, in which case, the rent shall
be abated during the unexpired portion of this Lease, effective upon the date
such damage occurred,

                                       8
<PAGE>

and Tenant shall pay to Landlord the amount of the deductible applicable to such
damage. Time is of the essence with respect to the delivery of such notices.

          (b) Subject to Section 10.(c), if this Lease is not terminated under
Section 10.(a), then Landlord shall restore the Premises to substantially its
previous condition, except that Landlord shall not be required to rebuild,
repair or replace any part of the partitions, fixtures, additions and other
improvements or personal property required to be covered by Tenant's insurance
under Section 9. If the Premises are untenantable, in whole or in part, during
the period beginning on the date such damage occurred and ending on the date of
substantial completion of Landlord's repair or restoration work plus a
reasonable period of time to allow Tenant to install its fixtures and equipment
in the Premises (not to exceed 30 days) (the "Repair Period"), then the rent for
                                              -------------
such period shall be reduced to such extent as may be fair and reasonable under
the circumstances (even if a Tenant Party caused such damage) and the Term shall
be extended by the number of days in the Repair Period.

          (c) If the Premises are destroyed or substantially damaged by any
peril not covered by the insurance maintained by Landlord or any Landlord's
Mortgagee (defined below) requires that insurance proceeds be applied to the
indebtedness secured by its Mortgage (defined below) or to the Primary Lease
(defined below) obligations, Landlord may terminate this Lease by delivering
written notice of termination to Tenant within 30 days after such destruction or
damage or such requirement is made known by any such Landlord's Mortgagee, as
applicable, whereupon all rights and obligations hereunder shall cease and
terminate, except for any liabilities of Tenant which accrued before this Lease
is terminated.

     11.  LIABILITY, INDEMNIFICATION, WAIVER OF SUBROGATION AND NEGLIGENCE.
          ----------------------------------------------------------------

          (a) Subject to Section 11.(b), Tenant shall indemnify, defend, and
hold harmless Landlord, its successors, assigns, agents, employees, contractors,
partners, directors, officers and affiliates (collectively, the "Indemnified
                                                                 -----------
Parties") from and against all fines, suits, losses, costs, liabilities, claims,
-------
demands, actions and judgments of every kind or character (1) recovered from or
asserted against any of the Indemnified Parties on account of any Loss (defined
below) to the extent that any such Loss arises out of or is caused by a Tenant
Party or any other person entering upon the Premises under or with a Tenant
Party's express or implied invitation or permission, (2) arising from or out of
the occupancy or use by a Tenant Party or arising from or out of any occurrence
in the Premises, howsoever caused, or (3) suffered by, recovered from or
asserted against any of the Indemnified Parties by the employees, agents,
contractors, or invitees of a Tenant Party. However, such indemnification of the
Indemnified Parties by Tenant shall not be applicable if such loss, damage, or
injury is caused by the negligence or willful misconduct of Landlord or any of
its agents, contractors, or employees. Subject to Section 11.(b) and Section
29, Landlord shall indemnify, defend, and hold harmless Tenant, its successors,
assigns, agents, employees, contractors, partners, directors, officers, and
affiliates from and against all fines, suits, losses, costs, liabilities,
claims, demands, actions and judgments of every kind and character caused by the
negligence or willful misconduct of Landlord or any of its duly authorized
agents or employees. "Loss" means any injury to or death of any person or
                      ----
persons or the damage to or theft, destruction, loss, or loss of use of any
property or inconvenience.

                                       9
<PAGE>

          (b) Landlord and Tenant each waives any claim it might have against
the other for any damage to or theft, destruction, loss, or loss of use of any
property, to the extent the same is insured against under any insurance policy
maintained by it that covers the Premises, Landlord's or Tenant's fixtures,
personal property, leasehold improvements, or business, or is required to be
insured against by the waiving party under the terms hereof, regardless of
whether the negligence or fault of the other party caused such loss; however,
Landlord's waiver shall not apply to any deductible amounts maintained by
Landlord under its insurance. Each party shall cause its insurance carrier to
endorse all applicable policies waiving the carrier's rights of recovery under
subrogation or otherwise against the other party.

     12.  USE.
          ---

          (a) The Premises shall be used only for general office use (corporate,
administrative, and professional), research and development use, and
manufacturing use and for such other lawful purposes as may be incidental
thereto; however, no retail sales may be made from the Premises. Tenant shall
not use the Premises to receive, store or handle any product, material or
merchandise that is explosive or highly inflammable or hazardous, except as
permitted under Section 25. Outside storage is prohibited, except as provided in
Section 29. Subject to Section 4.(a), Tenant shall be solely responsible for
complying with all Laws applicable to the use, occupancy, and condition of the
Premises. Tenant shall not permit any objectionable or unpleasant odors, smoke,
dust, gas, light, noise or vibrations to emanate from the Premises; nor take any
other action that would constitute a nuisance or would disturb, unreasonably
interfere with, or endanger Landlord or any other person; nor permit the
Premises to be used for any purpose or in any manner that would (1) void the
insurance thereon, (2) increase the insurance risk, or (3) cause the
disallowance of any sprinkler credits. Tenant shall pay to Landlord on demand
any increase in the cost of any insurance on the Premises incurred by Landlord,
which is caused by Tenant's use of the Premises or because Tenant vacates the
Premises.

          (b) Tenant and its employees and invitees shall have the exclusive
right to use all parking areas associated with the Premises, but Landlord shall
not be responsible for enforcing Tenant's parking rights against third parties.
Landlord, however, will provide Tenant with any documents it requests which
demonstrate Tenant's exclusive right to all parking areas associated with the
Premises. Landlord shall provide a minimum of 595 parking spaces at the
Premises.

     13.  INSPECTION. Landlord and Landlord's agents and representatives may
          ----------
enter the Premises during business hours to inspect the Premises; to make such
repairs as may be required or permitted under this Lease; to perform any
unperformed obligations of Tenant hereunder; and to show the Premises to
prospective purchasers, mortgagees, ground lessors, and (during the last 12
months of the Term) tenants. If such entrance is not in the case of an
emergency, such entrance shall be prohibited unless Tenant is provided with
reasonable notice (which may be given orally) of such entrance and such entrance
shall be done in such a way as to minimize interference with Tenant's business
to the extent reasonably practicable. During the last 12 months of the Term,
Landlord may erect a sign on the Premises indicating that the Premises are
available. Tenant shall notify Landlord in writing of its intention to vacate
the Premises at least 60 days before Tenant will vacate the Premises; such
notice shall specify the date on which Tenant intends to vacate the Premises
(the "Vacation Date"). At least 30 days before the Vacation Date, Tenant shall
      -------------
arrange to meet with

                                       10
<PAGE>

Landlord for a joint inspection of the Premises. After such inspection, the
parties will agree on what Tenant must perform based on Tenant's obligations as
set forth in Sections 5 and 16 of this Lease. If tenant refuses to participate
in such inspection, then Landlord may conduct such inspection and Landlord's
determination of the work Tenant is required to perform before the Vacation Date
shall be conclusive. If Tenant fails to perform such work before the Vacation
Date, then Landlord may perform such work at Tenant's cost. Tenant shall pay all
costs incurred by Landlord in performing such work within ten days after
Landlord's request therefor.

     14.  ASSIGNMENT AND SUBLETTING.
          -------------------------

          (a) Tenant shall not, without the prior written consent of Landlord
(which shall not be unreasonably withheld as provided in Section 31), (1)
assign, transfer, or encumber this Lease or any estate or interest herein,
whether directly or by operation of law, (2) permit any other entity to become
Tenant hereunder by merger, consolidation, or other reorganization (except as
provided below), (3) if Tenant is an entity other than a corporation whose stock
is publicly traded, permit the transfer of an ownership interest in Tenant so as
to result in a change in the current control of Tenant, (4) sublet any portion
of the Premises, (5) grant any license, concession, or other right of occupancy
of any portion of the Premises, or (6) permit the use of the Premises by any
parties other than Tenant (any of the events listed in Sections 14.(a)(1)
through 14.(a)(6) being a "Transfer"). It shall not be unreasonable for Landlord
                           --------
to withhold its consent to any transferee which intends to use Hazardous
Substances at the Premises. If Tenant requests Landlord's consent to a Transfer,
then Tenant shall provide Landlord with a written description of all terms and
conditions of the proposed Transfer, copies of the proposed documentation, and
the following information about the proposed transferee: name and address;
reasonably satisfactory information about its business and business history; its
proposed use of the Premises; banking, financial, and other credit information;
and general references sufficient to enable Landlord to determine the proposed
transferee's creditworthiness and character. Tenant shall reimburse Landlord for
its reasonable attorneys' fees and other expenses incurred in connection with
considering any request for its consent to a Transfer. If Landlord consents to a
proposed Transfer, then the proposed transferee shall deliver to Landlord a
written agreement whereby it expressly assumes the Tenant's obligations
hereunder (however, any transferee of less than all of the space in the Premises
shall be liable only for obligations under this Lease that are properly
allocable to the space subject to the Transfer, and only to the extent of the
rent it has agreed to pay Tenant therefor). Landlord's consent to a Transfer
shall not release Tenant from performing its obligations under this Lease, but
rather Tenant and its transferee shall be jointly and severally liable therefor.
Landlord's consent to any Transfer shall not waive Landlord's rights as to any
subsequent Transfers. If an Event of Default occurs while the Premises or any
part thereof are subject to a Transfer, then Landlord, in addition to its other
remedies, may collect directly from such transferee all rents becoming due to
Tenant and apply such rents against Tenant's rent obligations. Tenant authorizes
its transferees to make payments of rent directly to Landlord upon receipt of
notice from Landlord to do so.

          (b) If no Event of Default exists, all compensation received by Tenant
for or in connection with a Transfer in respect of the interval in question
that exceeds the Base Rent and Operating Expenses allocable to the portion of
the Premises covered thereby for the same interval shall be payable as follows:

                                       11
<PAGE>

              (1)   first, to Tenant until Tenant has received an amount equal
     to all actual, third-party, out-of-pocket costs incurred by Tenant in
     connection with such Transfer (including brokerage commissions, attorneys'
     fees and expenses, tenant-finish-work, other tenant inducements, and
     advertisement costs); and

              (2)   thereafter, 50% to Landlord and 50% to Tenant.

If an Event of Default exists, all such excess compensation shall be payable to
Landlord. Tenant shall hold all amounts it receives which are payable to
Landlord in trust and shall deliver all such amounts to Landlord within five
days after Tenant's receipt thereof.

          (c) Notwithstanding the foregoing, Tenant may Transfer all or part of
its interest in this Lease or all or part of the Premises (a "Permitted
                                                              ---------
Transfer") to the following types of entities (a "Permitted Transferee") without
--------                                          --------------------
the written consent of Landlord:

              (1)   an affiliate of Tenant;

              (2)   any corporation in which or with which Tenant, or its
     corporate successors or assigns, is merged or consolidated, in accordance
     with applicable statutory provisions governing merger and consolidation of
     corporations, so long as (A) Tenant's obligations hereunder are assumed by
     the corporation surviving such merger or created by such consolidation; and
     (B) the tangible net worth of the surviving or created corporation is not
     less than $100,000,000; or

              (3)   any corporation acquiring all or substantially all of
     Tenant's assets if such corporation's tangible net worth after such
     acquisition is not less than $100,000,000.

Tenant shall promptly notify Landlord of any such Permitted Transfer.

     15.  CONDEMNATION. If a material portion of the Premises is permanently
          ------------
taken for any public or quasi-public use by right of eminent domain or private
purchase in lieu thereof (a "Taking"), such that Tenant is unable to use the
                             ------
Premises for the purpose for which they were leased to Tenant, either party may
terminate this Lease by delivering to the other written notice thereof within 30
days after the Taking, in which case rent shall be abated during the unexpired
portion of the Term, effective on the date of such Taking. If (a) less than a
material portion of the Premises are subject to a Taking or (b) a material
portion of the Premises are subject to a Taking, but the Taking does not prevent
or materially interfere with Tenant's use of the Premises for the purpose for
which they were leased to Tenant, then neither party may terminate this Lease,
but the rent payable during the unexpired portion of the Term shall be reduced
to such extent as may be fair and reasonable under the circumstances. All
compensation awarded for any Taking shall be the property of Landlord and Tenant
assigns any interest it may have in any such award to Landlord; however,
Landlord shall have no interest in any award made to Tenant for loss of business
or goodwill, for the taking of Tenant's trade fixtures, or for relocation
expenses, if a separate award for such items is made to Tenant.

                                       12
<PAGE>

     16.  SURRENDER OF PREMISES; HOLDING OVER.
          -----------------------------------

          (a)   No act by Landlord shall be an acceptance of a surrender of the
Premises, and no agreement to accept a surrender of the Premises shall be valid
unless it is in writing and signed by Landlord. At the end of the Term or the
termination of Tenant's right to possess the Premises. Tenant shall (1) deliver
to Landlord the Premises with all improvements located thereon in good repair
and condition, reasonable wear and tear (subject however to Tenant's maintenance
obligations) excepted, and with the HVAC System and hot water equipment, light
and light fixtures (including ballasts), and overhead doors and related
equipment in good working order, (2) deliver to Landlord all keys to the
Premises, and (3) remove all signage placed on the Premises by or at Tenant's
request. All fixtures, alterations, additions, and improvements (whether
temporary or permanent) shall be Landlord's property and shall remain on the
Premises except as provided below. Tenant may remove all trade fixtures
(including the clean room, ultra-pure gas farm area, and ultra-pure water farm
area), furniture, and personal property placed in the Premises by Tenant (but
Tenant shall not remove any such item which was paid for, in whole or in part,
by Landlord). Additionally, if the Term has not been cancelled in accordance
with Section 27 hereof, Tenant shall remove such alterations, additions,
improvements, fixtures, equipment, wiring, cabling, furniture, and other
property as Landlord may request, provided such request is made within two
months after the end of the Term. All items not so removed shall, at the option
of Landlord, be deemed abandoned by Tenant and may be appropriated, sold,
stored, destroyed, or otherwise disposed of by Landlord without notice to Tenant
and without any obligation to account for such items and Tenant shall pay for
the costs incurred by Landlord in connection therewith. All work required of
Tenant under this Section 16.(a) shall be coordinated with Landlord and be done
in a good and workmanlike manner, in accordance with all Laws, and so as not to
damage the Premises. Tenant shall, at its expense, repair all damage caused by
any work performed by Tenant under this Section 16.(a).

          (b)   If Tenant fails to vacate the Premises at the end of the
 Term, then Tenant shall be a Tenant at will and Tenant shall pay, in addition
 to the other rent due hereunder, a daily base rental equal to 150% of the daily
 Base Rent payable during the last month of the Term, even if Landlord consents
 to such holdover, unless Landlord agrees otherwise in writing. Additionally,
 Tenant shall defend, indemnify, and hold harmless Landlord from any damage,
 liability and expense (including attorneys' fees and expenses) incurred because
 of such holding over. No payments of money by Tenant to Landlord after the Term
 shall reinstate, continue or extend the Term, and no extension of the Term
 shall be valid unless it is in writing and signed by Landlord and Tenant.

     17.  QUIET ENJOYMENT. Provided Tenant has fully performed its obligations
          ---------------
under this Lease, Tenant shall peaceably and quietly hold and enjoy the Premises
for the Term, without hindrance from Landlord or any party claiming by, through,
or under Landlord, but not otherwise.

     18.  EVENTS OF DEFAULT. Each of the following events shall constitute an
          -----------------
"Event of Default" under this Lease:
 ----------------

          (a)   Tenant's failure to pay rent when due and the continuance of
such failure for a period of ten days after Landlord has delivered to Tenant
written notice thereof;

                                       13
<PAGE>

          (b)   The filing of a petition by or against Tenant or any guarantor
of Tenant's obligations hereunder (1) in any bankruptcy or other insolvency
proceeding; (2) seeking any relief under any debtor relief Law; (3) for the
appointment of a liquidator, receiver, trustee, custodian, or similar official
for all or substantially all of Tenant's property or for Tenant's interest in
this Lease: or (4) for reorganization or modification of Tenant's capital
structure (however, if any such petition is filed against Tenant, then the
filing of such petition shall not constitute an Event of Default, unless it is
not dismissed within 120 days after the filing thereof).

          (c)   Tenant fails to discharge any lien placed upon the Premises in
violation of Section 22 within 20 days after Tenant has received written notice
of any such lien or encumbrance is filed against the Premises.

          (d)   Tenant fails to comply with any term, provision, or covenant of
this Lease (other than those listed in this Section 18) and such failure
continues for 30 days after written notice thereof to Tenant; however, if such
failure cannot be cured within such 30-day period and Tenant begins to cure such
failure within such 30-day period and thereafter diligently pursues such cure to
completion, such failure shall not be an Event of Default unless it is not cured
within 180 days after Landlord initially delivered to Tenant written notice of
the failure in question. Landlord may not terminate this Lease or terminate
Tenant's right to possess the Premises because of a default under this Section
18.(d) unless such default is material.

     19.  REMEDIES.
          --------

          (a)   Upon any Event of Default, Landlord may, in addition to all
other rights and remedies afforded Landlord hereunder or by Law, take any of the
following actions:

              (1)   Terminate this Lease by giving Tenant written notice
     thereof, in which event, Tenant shall pay to Landlord the sum of (A) all
     rent accrued hereunder through the date of termination, (B) all amounts due
     under Section 19.(b), and (C) an amount equal to (i) the total rent that
     Tenant would have been required to pay for the remainder of the Term
     discounted to present value at a per annum rate equal to the rate of
     interest set forth for 26-week U.S. governmental bills sold at a discount
     from face value in units of $10,000 to $1,000,000 as published on the date
     this Lease is terminated by The Wall Street Journal, Southwest Edition, in
     its listing of "Money Rates" under the heading "Treasury Bills" (or, if no
     such rate is published, the "Discount Rate" as published on such date under
     the "Money Rates" listing), minus (ii) the then present fair rental value
     of the Premises for such period, similarly discounted; or

              (2)   Terminate Tenant's right to possess the Premises without
     terminating this Lease by giving written notice thereof to Tenant, in
     which event Tenant shall pay to Landlord (A) all rent and other amounts
     accrued hereunder to the date of termination of possession, (B) all amounts
     due from time to time under Section 19.(b), and (C) all rent and other sums
     required hereunder to be paid by Tenant during the remainder of the Term,
     diminished by any net sums thereafter received by Landlord through
     reletting the Premises during such period. Landlord shall use reasonable
     efforts to relet the Premises on such terms and conditions as Landlord may
     determine (including a term different than the Term, rental

                                       14
<PAGE>

     concessions, and alterations to, and improvement of, the Premises);
     however, Landlord shall not be obligated to relet the Premises before
     leasing other portions of the business park of which the Building is a
     part. Landlord shall not be liable for, nor shall Tenant's obligations
     hereunder be diminished because of, Landlord's failure to relet the
     Premises or to collect rent due for such reletting. Tenant shall not be
     entitled to the excess of any consideration obtained by reletting over the
     rent due hereunder. Reentry by Landlord in the Premises shall not affect
     Tenant's obligations hereunder for the unexpired Term; rather, Landlord
     may, from time to time, bring action against Tenant to collect amounts due
     by Tenant, without the necessity of Landlord's waiting until the expiration
     of the Term. Unless Landlord delivers written notice to Tenant expressly
     stating that it has elected to terminate this Lease, all actions taken by
     Landlord to exclude or dispossess Tenant of the Premises shall be deemed to
     be taken under this Section 19.(a)(2). If Landlord elects to proceed under
     this Section 19.(a)(2), it may at any time elect to terminate this Lease
     under Section 19.(a)(l).

Additionally Landlord may perform Tenant's unperformed obligations hereunder
and, without notice, Landlord may alter locks or other security devices at the
Premises to deprive Tenant of access thereto, and Landlord shall not be required
to provide a new key or right of access to Tenant.

          (b)   Tenant shall pay to Landlord all costs incurred by Landlord
(including court costs and reasonable attorneys' fees and expenses) in (1)
obtaining possession of the Premises, (2) removing and storing Tenant's or any
other occupant's property, (3) repairing, restoring, altering remodeling, or
otherwise putting the Premises into condition acceptable to a new tenant, (4) if
Tenant is dispossessed of the Premises and this Lease is not terminated,
reletting all or any part of the Premises (including brokerage commissions, cost
of tenant finish work, and other costs incidental to such reletting), (5)
performing Tenant's obligations which Tenant failed to perform, and (6)
enforcing, or advising Landlord of, its rights, remedies, and recourses.
Landlord's acceptance of rent following an Event of Default shall not waive
Landlord's rights regarding such Event of Default. Landlord's receipt of rent
with knowledge of any default by Tenant hereunder shall not be a waiver of such
default, and no waiver by Landlord of any provision of this Lease shall be
deemed to have been made unless set forth in writing and signed by Landlord. No
waiver by Landlord of any violation or breach of any of the terms contained
herein shall waive Landlord's rights regarding any future violation of such term
or violation of any other term. If Landlord repossesses the Premises pursuant to
the authority herein granted, then Landlord shall have the right to (A) keep in
place and use or (B) remove and store, at Tenant's expense, all of the
furniture, fixtures, equipment and other property in the Premises, including
that which is owned by or leased to Tenant at all times before any foreclosure
thereon by Landlord or repossession thereof by any lessor thereof or third party
having a lien thereon. Landlord may relinquish possession of all or any portion
of such furniture, fixtures, equipment and other property to any person (a
"Claimant") who presents to Landlord a copy of any instrument represented by
 --------
Claimant to have been executed by Tenant (or any predecessor of Tenant) granting
Claimant the right under various circumstances to take possession of such
furniture, fixtures, equipment or other property, without the necessity on the
part of Landlord to inquire into the authenticity or legality of the instrument.
Landlord may, at its option and without prejudice to or waiver of any rights it
may have, (i) escort Tenant to the Premises to retrieve any personal belongings
of Tenant and/or its employees or (ii) obtain a list from Tenant of the personal
property of Tenant and/or its employees, and make such property available to
Tenant and/or Tenant's employees; however, Tenant first shall pay in cash all
costs and estimated expenses to be incurred

                                       15
<PAGE>

in connection with the removal of such property and making it available. The
rights of Landlord herein stated are in addition to any and all other rights
that Landlord has or may hereafter have at Law or in equity, and Tenant agrees
that the rights herein granted Landlord are commercially reasonable.

     20.  LANDLORD'S DEFAULT. Except as provided below in this Section 20,
          ------------------
Tenant's exclusive remedy for Landlord's failure to perform its obligations
under this Lease shall be limited to damages, injunctive relief, or specific
performance; in each case, Landlord's liability or obligations with respect to
any such remedy shall be limited as provided in the last paragraph of this
Section 20. Landlord shall be in default under this Lease if Landlord fails to
perform any of its obligations hereunder within 30 days after written notice
from Tenant specifying such failure; however, if such failure cannot reasonably
be cured within such 30-day period, but Landlord commences to cure such failure
within such 30-day period, thereafter diligently pursues the curing thereof to
completion, and such failure is cured within 180 days after Tenant first
delivered to Landlord written notice thereof, then Landlord shall not be in
default hereunder or liable for damages therefor. Unless Landlord fails to so
cure such default after such notice, Tenant shall not have any remedy or cause
of action by reason thereof. If Landlord fails to perform its obligations within
the time periods specified in the previous sentences of this Section 20, and
such failure adversely affects Tenant's use of the Premises, then Tenant may
perform such obligations and Landlord shall reimburse Tenant all actual
third-party, out-of-pocket costs incurred by Tenant in connection with
performing such obligations (other than those which would constitute an
Operating Expense had Landlord performed such work, in which case, Landlord
shall not be obligated to reimburse Tenant therefor) within 30 days after Tenant
delivers to Landlord written demand therefor, accompanied by invoices
substantiating Tenant's claim. If Landlord fails to pay such amount within such
30-day period, Tenant may offset against its obligation to pay Base Rent such
costs, unless Landlord is in good faith disputing such claim, in which case,
Tenant may offset the amount of such claim which is not in dispute. If Landlord
is disputing Tenant's claim for any amounts due under this Section 20, Tenant
may initiate the arbitration proceedings provided herein by delivering to
Landlord written notice thereof (an "Arbitration Notice"). If Tenant delivers an
                                     ------------------
Arbitration Notice, Landlord and Tenant shall, within five days after the
delivery of such notice, jointly appoint an arbitrator with at least five-years'
real estate experience who has not performed substantial work for either party
during the previous five-year period. If the parties cannot agree upon such
arbitrator within such five-day period, then either Landlord or Tenant may
request that the Dallas office of the American Arbitration Association (the
"AAA") appoint an arbitrator meeting the qualifications specified in the
 ---
previous sentence. The arbitrator selected by the AAA shall be binding on
Landlord and Tenant. The arbitrator shall thereafter resolve the dispute within
15 days after his appointment, based on evidence submitted to him by Landlord
and Tenant and such other evidence as he may request. However, the arbitrator
shall conduct such proceedings as expeditiously and inexpensively as possible
and, in connection therewith, may establish such rules for the proceedings as he
deems necessary, which will be binding on all parties to the arbitration
proceeding. Accordingly, the arbitrator may (1) dispense with any formal rules
of evidence and allow hearsay testimony so as to limit the number of witnesses
required, (2) limit the time for presentation of any party's case as well as the
amount of information or number of witnesses to be presented in connection with
any hearing, and (3) impose any other rules which the arbitrator believes are
appropriate to resolve the dispute as quickly and inexpensively as possible. The
arbitrator's decision shall be binding on the parties.

                                       16
<PAGE>

The non-prevailing party shall pay all costs of the arbitration, including all
costs incurred by the prevailing party (including attorneys' fees and expenses).

          Tenant's right to perform the work under this Section 20 is subject to
the following conditions: (A) all such work shall be performed in a good and
workmanlike manner, in accordance with Law, and in a manner so as not to affect
any existing warranties with respect to the Building's Structure; (B) all such
work shall be performed in a manner so as not to alter any portion of the
Building's Structure (except for necessary alterations required to comply with
Law), unless Landlord otherwise consents thereto (if such work would alter any
portion of the Building's Structure, all such work shall be performed in
accordance with plans and specifications approved by Landlord [which approval
shall not be unreasonably withheld], whose approval shall be deemed given if
Landlord fails to disapprove any submitted plans and specifications within ten
business days after their submission to Landlord); (C) all such work shall be
performed by contractors which maintain commercial liability insurance on an
occurrence basis in an amount not less than $1,000,000 per occurrence naming
Landlord as an additional insured; and (D) Tenant delivers to Landlord
"as-built" plans of the work performed by Tenant. If Landlord defaults in its
obligations under Section 4.(b) (after the expiration of any applicable cure
periods) and Tenant performs and pays for such obligations, there shall be
excluded from the calculation of Operating Expense the management fees payable
during the period such default existed.

          Any recourse against Landlord under this Lease shall be limited to
Landlord's interest in the Premises and rents derived therefrom, and neither
Landlord nor Landlord's owners shall have any personal liability therefor.
Nothing in this Lease shall preclude Tenant from seeking injunctive relief. The
obligations of Landlord under this Lease will be binding upon Landlord only for
obligations accruing during the period of its ownership of the Premises and not
thereafter.

     21.  MORTGAGES.
          ---------

          (a)   Subject to the last sentence of this Section 21.(a), this Lease
shall be subordinate to any deed of trust, mortgage or other security instrument
(a "Mortgage") and any ground lease, master lease, or primary lease (a "Primary
    --------                                                            -------
Lease") that now or hereafter covers any portion of the Premises (the mortgagee
-----
under any Mortgage or the lessor under any Primary Lease is referred to herein
as "Landlord's Mortgagee"), and to increases, renewals, modifications,
    --------------------
consolidations, replacements, and extensions thereof. However, any Landlord's
Mortgagee may elect to subordinate its Mortgage or Primary Lease (as the case
may be) to this Lease by delivering written notice thereof to Tenant. Except as
provided in the last sentence of this Section 21.(a), no further instrument
shall be required to effect such subordination; however, Tenant shall from time
to time within ten days after request therefor, execute any instruments that may
be required by any Landlord's Mortgagee to evidence the subordination of this
Lease to any such Mortgage or Primary Lease. Landlord hereby represents and
warrants to Tenant that the Premises is not currently encumbered by a Mortgage
or a Primary Lease. As a condition to the subordination of this Lease to a
Mortgage or a Primary Lease, the Landlord's Mortgagee shall execute and deliver
to Tenant a commercially reasonable non-disturbance, subordination, and
attornment agreement.

          (b)   Tenant shall attorn to any party succeeding to Landlord's
interest in the Premises, whether by purchase, foreclosure, deed in lieu of
foreclosure, power of sale, termination

                                       17
<PAGE>

of lease, or otherwise, upon such party's request, and shall execute such
agreements confirming such attornment as such party may reasonably request.
Tenant shall not seek to enforce any remedy it may have for any default on the
part of Landlord without first giving written notice by certified mail, return
receipt requested, specifying the default in reasonable detail to any Landlord's
Mortgagee whose address has been given to Tenant, and affording such Landlord's
Mortgagee a reasonable opportunity to perform Landlord's obligations hereunder.

          (c)   Notwithstanding any such attornment or subordination of a
Mortgage or Primary Lease to this Lease, the Landlord's Mortgagee shall not be
liable for any acts of any previous landlord (but the Landlord's Mortgagee shall
be subject to the offset rights of Tenant under Section 20) and shall not be
bound by any amendment to which it did not consent in writing nor any payment
of rent made more than one month in advance.

     22.  ENCUMBRANCES. Tenant has no authority, express or implied, to create
          ------------
or place any lien or encumbrance of any kind or nature whatsoever upon, or in
any manner to bind Landlord's property or the interest of Landlord or Tenant in
the Premises or to charge the rent for any claim in favor of any person dealing
with Tenant, including those who may furnish materials or perform labor for any
construction or repairs. Tenant shall pay or cause to be paid all sums due for
any labor performed or materials furnished in connection with any work performed
on the Premises by or at the request of Tenant. Tenant shall give Landlord
immediate written notice of the placing of any lien or encumbrance against the
Premises.

     23.  MISCELLANEOUS.
          -------------

          (a)   Words of any gender used in this Lease shall include any other
gender, and words in the singular shall include the plural, unless the context
otherwise requires. The captions inserted in this Lease are for convenience only
and in no way affect the interpretation of this Lease. The following terms shall
have the following meanings: "Laws" shall mean all federal, state, and local
                              ----
laws, rules, and regulations; all court orders, governmental directives, and
governmental orders; and all restrictive covenants affecting the Property, and
"Law" shall mean any of the foregoing; "affiliate" shall mean any person or
 ---                                    ---------
entity which, directly or indirectly, controls, is controlled by, or is under
common control with the party in question; "Tenant Party" shall include Tenant,
                                            -----------
any assignees claiming by, through, or under Tenant, any subtenants claiming by,
through, or under Tenant, and any of their respective agents, contractors,
employees, and invitees; and "including" shall mean including, without
                              ---------
limitation. The normal rule of construction that any ambiguities be resolved
against the drafting party shall not apply to the interpretation of this Lease
or any exhibits or amendments hereto.

          (b)   Landlord may transfer and assign, in whole or in part, its
rights and obligations in the Building and property that are the subject to this
Lease, in which case Landlord shall have no liability hereunder for any
obligations arising from and after the transfer or assignment and Tenant shall
attorn to such transferee, provided that the transferee assumes the obligations
of Landlord hereunder in writing (including the return of the Security Deposit).
Each party shall furnish to the other, promptly upon demand, a corporate
resolution, proof of due authorization by partners, or other appropriate
documentation evidencing the due authorization of such party to enter into this
Lease.

                                       18
<PAGE>

          (c)   Except for the payment of rent and the maintenance of insurance,
whenever a period of time is herein prescribed for action to be taken by
Landlord or Tenant, such party shall not be liable or responsible for, and there
shall be excluded from the computation for any such period of time, any delays
due to strikes, riots, acts of God, shortages of labor or materials, war, Laws
or any other causes of any kind whatsoever which are beyond the control of the
party in question.

          (d)   Tenant shall, from time to time, within 20 days after request of
Landlord, deliver to Landlord, or Landlord's designee, a certificate of
occupancy for the Premises, financial statements for itself and any guarantor of
its obligations hereunder, evidence reasonably satisfactory to Landlord that
Tenant has performed its obligations under this Lease (including evidence of the
payment of the Security Deposit), and an estoppel certificate stating that this
Lease is in full effect, the date to which rent has been paid, the unexpired
Term and such other factual matters pertaining to this Lease as may be
reasonably requested by Landlord. Tenant's obligation to furnish the
above-described items in a timely fashion is a material inducement for
Landlord's execution of this Lease.

          (e)   This Lease constitutes the entire agreement of the Landlord
(including all exhibits attached hereto which are incorporated herein) and
Tenant with respect to the subject matter of this Lease, and contains all of the
covenants and agreements of Landlord and Tenant with respect thereto. Landlord
and Tenant each acknowledge that no representations, inducements, promises or
agreements, oral or written, have been made by Landlord or Tenant, or anyone
acting on behalf of Landlord or Tenant, which are not contained herein, and any
prior agreements, promises, negotiations, or representations not expressly set
forth in this Lease are of no effect. This Lease may not be altered, changed or
amended except by an instrument in writing signed by both parties hereto.

          (f)   All obligations of either party hereunder not fully performed by
the end of the Term shall survive, including all payment obligations of either
party and all of Tenant's obligations concerning the condition and repair of the
Premises. After Tenant has satisfied its obligations under the Lease, Landlord
shall promptly return the Security Deposit with interest to the Tenant as
specified in Section 2.(b).

          (g)   If any provision of this Lease is illegal, invalid or
unenforceable, then the remainder of this Lease shall not be affected thereby,
and in lieu of each such provision, there shall be added, as a part of this
Lease, a provision as similar in terms to such illegal, invalid or unenforceable
clause or provision as may be possible and be legal, valid and enforceable.

          (h)   All references in this Lease to "the date hereof" or similar
references shall be deemed to refer to the last date, in point of time, on
which all parties hereto have executed this Lease.

          (i)   Landlord and Tenant each warrant to the other that it has not
dealt with any broker or agent in connection with this Lease, other than
Trammel1 Crow Dallas Industrial, Ltd. and CB Commercial Real Estate Group, Inc.,
whose commissions shall be paid by Landlord. Tenant and Landlord shall each
indemnify the other against all costs, attorneys' fees, and other liabilities
for commissions or other compensation claimed by any other broker or agent
claiming the same by, through, or under the indemnifying party.

                                       19
<PAGE>

          (j) If and when included within the term "Tenant," as used in this
instrument there is more than one person, firm or corporation, all shall
jointly arrange among themselves for their joint execution of a notice
specifying an individual at a specific address within the continental United
States for the receipt of notices and payments to Tenant. All parties included
within the terms "Landlord" and "Tenant," respectively, shall be bound by
notices given in accordance with the provisions of Section 24 to the same effect
as if each had received such notice.

          (k) The terms and conditions of this Lease are confidential and
neither Landlord nor Tenant shall disclose the terms of this Lease to any third
party except as may be required by Law or to enforce its rights hereunder.

          (l) Each of Landlord and Tenant shall pay interest on all past-due
amounts owing from it to the other from the date due until paid at the maximum
lawful rate. In no event, however, shall the charges permitted under this
Section 23.(l) or elsewhere in this Lease, to the extent they are considered to
be interest under applicable Law, exceed the maximum lawful rate of interest.

     24.  NOTICES. Each provision of this instrument or of any applicable Laws
          -------
and other requirements with reference to the sending, mailing or delivering of
notice or the making of any payment hereunder shall be deemed to be complied
with when and if the following steps are taken:

          (a) All rent shall be payable to Landlord at the address for Landlord
set forth below or at such other address as Landlord may specify from time to
time by written notice delivered in accordance herewith. Tenant's obligation to
pay rent shall not be deemed satisfied until such rent has been actually
received by Landlord.

          (b) All payments required to be made by Landlord to Tenant hereunder
shall be payable to Tenant at the address set forth below, or at such other
address within the continental United States as Tenant may specify from time to
time by written notice delivered in accordance herewith.

          (c) Any written notice or document required or permitted to be
delivered hereunder shall be deemed to be delivered upon the earlier to occur of
(1) tender of delivery (in the case of a hand-delivered notice), (2) deposit in
the United States Mail, postage prepaid, Certified Mail, or (3) receipt by
facsimile transmission, in each case, addressed to the parties hereto at the
respective addresses set out below, or at such other address as they have
theretofore specified by written notice delivered in accordance herewith. If
Landlord has attempted to deliver notice to Tenant at Tenant's address reflected
on Landlord's books but such notice was returned or acceptance thereof was
refused, then Landlord may post such notice in or on the Premises, which notice
shall be deemed delivered to Tenant upon the posting thereof.

     25.   HAZARDOUS WASTE. The term "Hazardous Substances," as used in this
           ---------------            --------------------
Lease shall mean pollutants, contaminants, toxic or hazardous wastes, or any
other substances, the removal of which is required or the use of which is
restricted, prohibited or penalized by any "Environmental Law," which term shall
                                            ----------------
mean any Law relating to health pollution, or protection of the environment.
Tenant hereby agrees that (a) no activity will be conducted on the Premises that
will produce any Hazardous Substances, except for such activities that are part
of the ordinary course

                                       20
<PAGE>

of Tenant's business activities (the "Permitted Activities") provided such
                                     --------------------

Permitted Activities are conducted in accordance with all Environmental Laws;
(b) the Premises will not be used in any manner for the storage of any Hazardous
Substances except for storage of such materials that are used in the ordinary
course of Tenant's business (the "Permitted Materials") provided such Permitted
                                  -------------------
Materials are properly stored in a manner and location satisfying all
Environmental Laws; (c) no portion of the Premises will be used as a landfill
or a dump; (d) Tenant will not install any underground tanks of any type; (e)
Tenant will not allow any surface or subsurface conditions to exist or come into
existence that constitute, or with the passage of time may constitute a public
or private nuisance; and (f) Tenant will not permit any Hazardous Substances to
be brought onto the Premises, except for the Permitted Materials, and if so
brought or found located thereon, the same shall be immediately removed by
Tenant, with proper disposal, and all required cleanup procedures shall be
diligently undertaken pursuant to all Environmental Laws. If at any time during
or after the Term, the Premises are found to be so contaminated or subject to
such conditions, Tenant shall defend, indemnify and hold Landlord harmless from
all claims, demands, actions, liabilities, costs, expenses, damages and
obligations of any nature arising from or as a result of the use of the Premises
by a Tenant Party. Tenant will maintain on the Premises a list of all materials
stored at the Premises for which a material safety data sheet (an "MSDS") was
                                                                   ----
issued by the producers or manufacturers thereof, together with copies of the
MSDS's for such materials, and shall deliver such list and MSDS copies to
Landlord upon Landlord's request therefor. Except for Landlord Hazardous
Substances (defined below), Tenant shall remove all Permitted Materials and
other Hazardous Substances from the Premises in a manner acceptable to Landlord
before the earlier of the date Tenant vacates the Premises and the date Tenant's
right to possess the Premises ends. Landlord may enter the Premises and conduct
environmental inspections and tests therein as it may require from time to time,
provided that Landlord shall use reasonable efforts to minimize the interference
with Tenant's business. Such inspections and tests shall be conducted at
Landlord's expense, unless they reveal the presence of Hazardous Substances
(other than Permitted Materials and Landlord Hazardous Substances) or that
Tenant has not complied with the requirements set forth in this Section 25, in
which case Tenant shall reimburse Landlord for the cost thereof within ten days
after Landlord's request therefor.

          Notwithstanding the foregoing, within 30 days after Tenant vacates
the Premises, Tenant shall, at its expense, deliver to Landlord a Phase I
environmental report prepared by a reputable environmental engineer reasonably
acceptable to Landlord (and, if such report indicates the need for a Phase II
report or other reports, such additional reports prepared by such an engineer)
indicating that no Hazardous Substances exist on the Property. If any such
report reveals that any Hazardous Substances (other than Landlord Hazardous
Substances) exist on the Property, Tenant shall remove all such substances in a
manner acceptable to Landlord in its sole discretion.

          Landlord shall be responsible for all Hazardous Substances located on
the Property on the Commencement Date which were not placed on the property by a
Tenant Party and all Hazardous Substances placed on the Premises by Landlord or
its agents, contractors or employees (collectively, "Landlord Hazardous
                                                     ------------------
Substances"). Additionally, if Tenant is prohibited from using the Premises for
----------
three consecutive business days because of the presence of any Landlord
Hazardous Substances which could reasonably be expected to pose a health risk to
the occupants of the Premises and Tenant ceases using the Premises as a result
thereof, then Tenant's obligation to pay Base Rent and Operating Expenses shall
be abated until such time as Tenant may reasonably use the Premises.

                                       21
<PAGE>

     26.  LANDLORD'S LIEN. Landlord hereby waives its statutory landlord's lien
          ---------------
against Tenant's property in the Premises.

     27.  TENANT'S CANCELLATION RIGHT. Provided that no Event of Default exists
          ---------------------------
when Tenant delivers the Cancellation Notice or on the cancellation date,
Tenant may cancel this Lease effective as of the last day of any calendar month
after the 60th full calendar month of the Term by delivering to Landlord at
least nine months before the cancellation date (a) written notice thereof and
(b) the Cancellation Fee (defined below). The "Cancellation Fee" shall equal the
                                               ----------------
sum of $1,866,000 plus the amount that would be outstanding on a hypothetical
loan on the cancellation date assuming (1) an original principal balance equal
to the Leasing Costs (defined below), (2) an interest rate of 11% per annum, (3)
the loan is payable in equal monthly installments of principal and interest,
beginning on the first day of the first full calendar month of the Term and
ending on the first day of the last scheduled month of the Term (assuming the
Lease had not been terminated), and (4) all payments were made before the
cancellation date. The term "Leasing Costs" shall mean all costs incurred by
                             -------------
Landlord in leasing the space to Tenant for leasing commissions and attorneys'
fees and expenses. As a condition to the effectiveness of Tenant's cancellation
right, Tenant shall pay to Landlord prior to the cancellation date any past-due
amounts then outstanding under the Lease. If Tenant fails timely to deliver the
Cancellation Fee or the cancellation notice or is otherwise unable to exercise
this cancellation option, then Tenant's right to cancel this Lease under this
Section 27 shall expire; time is of the essence with respect thereto.

     28.  SECURITY SERVICE. Landlord shall have no obligation whatsoever to
          ----------------
provide security services to the Premises; however, Tenant may provide such
services at its sole expense, in which case, Tenant shall defend, indemnify, and
hold harmless Landlord from any liability arising in connection with the
provision of such security service.

     29.  TENANT'S OPERATIONAL AREAS. In connection with its use of the
          --------------------------
Premises and subject to compliance with Section 25 hereof, Tenant may install,
operate and maintain an ultra-pure gas farm area, an ultra-pure water farm area,
a barrel storage/hazardous waste area, and mechanical area ("Tenant's
                                                             --------
Operational Areas") on the exterior of the Premises at a location reasonably
-----------------
acceptable to Landlord, provided that the installation, maintenance, use, and
operation thereof complies with all Laws, and Tenant receives all approvals,
consents, and permits required under Law before the installation, maintenance,
use and operation thereof. Before beginning the installation of any such item,
Tenant shall deliver to Landlord final plans and specifications therefor
prepared by an engineer reasonably approved by Landlord setting forth in detail
the design, location, size and method of installation for Landlord's review and
approval (which shall not be unreasonably withheld), together with evidence
reasonably satisfactory to Landlord that all Laws have been satisfied.
Landlord's approval of any such plans and specifications shall not constitute a
representation or warranty by Landlord that such plans and specifications comply
with Law; such compliance shall be the sole responsibility of Tenant. Upon
approval of the plans and specifications therefor and the size and location
thereof, Tenant may install the Tenant Operational Areas provided that such work
is coordinated with Landlord and is performed in a good and workmanlike manner,
in accordance with Law and the plans and specifications therefor and in a manner
so as not to damage the Premises; thereafter, Tenant shall use, maintain, and
operate the Tenant Operational Areas in a good, clean and safe condition and in
accordance with all Laws. Tenant shall repair all damage caused by the
installation, use, maintenance, operation, or removal of the Tenant Operational

                                       22
<PAGE>

Areas and, upon its removal, restore the portions of the Premises where they
were located to their condition immediately before the installation thereof. If
Tenant fails to do so within 30 days after Landlord's request, Landlord may
perform such work and Tenant shall pay to Landlord all reasonable costs
incurred in connection therewith within 30 days after Landlord's written
request therefor. Tenant shall immediately remove from the area surrounding the
Tenant Operational Areas any spills or other leaks of fluid or Hazardous
Substances. Additionally, Tenant shall ensure that the Tenant Operational Areas
are properly exhausted at all times so no odors emanate therefrom. The Tenant
Operational Areas shall be installed, used, maintained, operated, and removed at
Tenant's risk and expense and Tenant shall maintain insurance in respect thereof
reasonably satisfactory to Landlord, listing Landlord, as an additional insured.
It is the intention of the parties that Tenant bear all risks relating to the
installation, use, maintenance, operation, and removal of the Tenant Operational
Areas; therefore, Tenant shall defend, indemnify, and hold harmless Landlord,
its agents, and their respective affiliates from all losses, claims, costs, and
liabilities arising in connection with or relating to the installation,
maintenance, use, operation, and removal of the Tenant Operational Areas,
including, without limitation, that arising from Landlord's negligence (other
than its sole or gross negligence), specifically including situations where
Landlord or its contractors, agents, or employees are jointly, concurrently or
comparatively negligent with a Tenant Party (unless the acts of Landlord or its
agents, contractors, or employees are found to have contributed to more than 30%
of the liability in question).

     30.  LANDLORD'S BANKRUPTCY. In the event that the obligations of Landlord
          ---------------------
under this Lease are not performed during the pendency of a bankruptcy or
insolvency proceeding involving the Landlord as the debtor, or following the
rejection of this Lease by Landlord in accordance with Section 365 of the
United States Bankruptcy Code, then notwithstanding any provision of this Lease
to the contrary, Tenant shall have the right to set off against rents next due
and owing under this Lease (a) any and all damages caused by such non-
performance of Landlord's obligations under this Lease by Landlord, debtor-in-
possession, or the bankruptcy trustee, and (b) any and all damages caused by the
non-performance of Landlord's obligations under this Lease following any
rejection of this Lease by Landlord in accordance with Section 365 of the United
States Bankruptcy Code.

     31.  CONSENT. If either party's consent is required hereunder for the
          -------
other party to take any action, then the party whose consent is required (the
"Consenting Party") shall not unreasonably withhold such consent, regardless of
 ----------------
whether the provision addressing such matter specifically states that Landlord's
consent is not to be unreasonably withheld. If the Consenting Party fails to
respond to a request for its consent or approval within ten business days after
it has received a written request therefor, together with all information
reasonably necessary for it to make an informed decision regarding the matter in
question, then such party's consent shall be deemed granted. If the Consenting
Party refuses to give its consent to the matter in question, then it shall
specify in reasonable detail the reasons therefor.

     32.  COUNTERPARTS; FACSIMILE SIGNATURES. Landlord and Tenant may execute
          ----------------------------------
this Lease in any number of counterparts with the same effect as if they had
signed the same document. Execution of this Lease may be effected by facsimile
transmission.

                                       23
<PAGE>

     33.  EMERGENCY REPAIRS BY TENANT. Tenant may make repairs to the Building's
          ---------------------------
Structure in case of an emergency to avoid imminent damage to property or
injury to persons, without Landlord's prior written consent; however, any such
work shall be limited to the extent necessary to alleviate such imminent risk of
damage and injury and is done in accordance with Law and in a good and
workmanlike manner so as not to affect any insurance coverages applicable
thereto. Before making any such repairs, Tenant shall notify Landlord of the
damage necessitating the repair in question and afford Landlord a reasonable
opportunity to perform such work (taking into account the exigency of the
situation). If Tenant makes any repairs under this Section 33 that Landlord
would otherwise have been required to pay for under Section 4.(a), then
Landlord shall reimburse to Tenant the costs of such repairs within 30 days
after Tenant delivers to Landlord written evidence substantiating all such
costs.

     Executed by Tenant on December 18, 1997.

TENANT:                        MILLIPORE CORPORATION, a Massachusetts
                               corporation

                               By: /s/ J. Edward Lary
                                   --------------------------------------------
                                        J. Edward Lary, Corporate Vice President
                               Address:     80 Ashby Road
                                            Bedford, Massachusetts 07130
                               Telephone:   (781) 533-5516
                               Fax:         (781) 533-3120

     Executed by Landlord on December 19th, 1997.

LANDLORD:                      EBP 3, LTD., a Texas limited partnership
                               By:    MIT Unsecured, Inc., a California
                                      corporation, its general partner

                                      By: /s/ Timothy B. Keith
                                         -----------------------------------
                                           Timothy B. Keith, Vice President

                                      Address: c/o Bob Dobbin
                                                   455 Market St #1700
                                                   San Francisco, CA 94105
                                      Telephone:   415 228 3900
                                      Fax:         415 284 2840
                                      w/or copy to:
                                                   1445 Ross Avenue
                                                   49th Floor
                                                   Dallas, TX 75202
                                                   Telephone: 214 978 8512
                                                   Fax: 214 855 6792

                                       24
<PAGE>

                                  EXHIBIT A-1

                               Legal Description

BEING a 13.894 acre tract out of the Rufus Sewell Survey, Abstract No. 875,
Collin County, Texas; said tract being part of Lot 1, Block 1, Enterprises
Addition No. 2, an addition to the City of Allen, Texas according to the plat
recorded in Cabinet G, Page 457 of the Plat Records of Collin County, Texas;
said 13.894 acre tract being more particularly described as follows:

COMMENCING, at a 1/2-inch iron rod found at the intersection of the south right-
of-way line of Bethany Drive (a 110-foot wide right-of-way) and the east right-
of-way line of Enterprise Boulevard (a 60-foot wide right-of-way); said point
being the northwest corner of said Lot 1, Block 1;

     THENCE, South 20 degrees, 33 minutes, 10 seconds East, along the said east
     line of Enterprise Boulevard and the west line of said Lot 1, a distance of
     153.71 feet to a l/2-inch iron rod found at the beginning of a curve to the
     right whose center bears South 69 degrees, 26 minutes, 50 seconds West, a
     distance of 180.00 feet from said point;

     THENCE, in a southerly direction continuing along the said east line of
     Enterprise Boulevard and said curve to the right, through a central angle
     of 34 degrees, 36 minutes, 10 seconds, an arc distance of 108.71 feet to a
     l/2-inch iron rod found at the end of said curve;

     THENCE, South 14 degrees, 03 minutes, 00 seconds West, continuing along the
     said east line of said Enterprise Boulevard, a distance of 511.09 feet to a
     1/2-inch iron rod found at an angle point;

     THENCE, South 11 degrees, 30 minutes, 00 seconds West, continuing along the
     said east line of Enterprise Boulevard, a distance of 315.97 feet to a
     1/2-inch iron rod with "Pacheco Koch" cap set at the POINT OF BEGINNING;

THENCE, South 68 degrees, 03 minutes, 17 seconds East, departing the said east
line of Enterprise Boulevard and the west line of said Lot 1, a distance of
684.35 feet to a l/2-inch iron rod with "Pacheco Koch" cap set for corner in the
west right-of-way line of Southern Pacific Railroad (a 100-foot wide railroad
right-of-way) and the east line of said Lot 1;

THENCE, South 22 degrees, 08 minutes, 57 seconds West, along the said west line
of Southern Pacific Railroad and the east line of said Lot 1, a distance of
180.01 feet to a l/2-inch iron rod found at the beginning of a curve to the
right whose center bears North 68 degrees, 05 minutes, 56 seconds West, a
distance of 2814.79 feet from said point;

                                       25
<PAGE>

THENCE, in a southwesterly direction along the said west line of Southern
Pacific Railroad and said curve to the right, through a central angle of 19
degrees, 11 minutes, 30 seconds, an arc distance of 942.84 feet to a 1/2-inch
iron rod with "Pacheco Koch" cap set for corner;

THENCE, North 78 degrees, 30 minutes, 00 seconds West, departing the said west
line of Southern Pacific Railroad and the east line of said Lot 1, a distance of
318.84 feet to a 1/2-inch iron rod with "Pacheco Koch" cap set for corner in the
said east line of Enterprise Boulevard and the west line of said Lot 1; said
point being on a curve to the left whose center bears North 77 degrees, 49
minutes, 24 seconds West, a distance of 320.00 feet from said point;

THENCE, in a northeasterly direction along the said east line of Enterprise
Boulevard and said curve to the left, through a central angle of 00 degrees, 40
minutes, 36 seconds, an arc distance of 3.78 feet to a 1/2-inch iron rod found
at the end of said curve;

THENCE, North 11 degrees, 30 minutes, 00 seconds East, continuing along the said
east line of Enterprise Boulevard, a distance of 1179.06 feet to the POINT OF
BEGINNING;

CONTAINING, 605,203 square feet of 13.894 acres of land, more or less.

                                       26
<PAGE>

                                  EXHIBIT A-2

                         [BUILDING PLAN APPEARS HERE]

                                     A-2-1

<PAGE>

                                   EXHIBIT B
                                   ---------

     1. Construction of Improvements. Landlord shall diligently construct the
        ----------------------------
Building Shell in accordance with the plans and specifications prepared by the
architect of record, Merriman & Associates, dated August 22, 1997, and last
revised November 6, 1997, and minor change orders thereto (the "Shell Plans"),
                                                                -----------
in a good and workmanlike manner using materials specified in the Shell Plans
and in compliance with Law (defined below). The Building Shell is referred to as
the "Improvements". Landlord assumes no liability for special, consequential, or
     ------------
incidental damages of any kind whatsoever in connection with the design or
construction of the Improvements, and makes no representations, warranties, or
guaranties regarding the same, expressed or implied, including, without
limitation, warranties of merchantability, fitness for a particular purpose, or
of habitability, except as expressly set forth herein. Landlord represents and
warrants to Tenant that upon completion of the Building Shell the exterior
portions of the Premises shall comply with Title III of the American
Disabilities, Act of 1990, the Texas Elimination of Architectural Barriers Act,
and all rules and regulations and guidelines promulgated under either of such
acts, as amended from time to time (the "Disabilities Acts"), shall comply with
                                         -----------------
all other Laws, and shall not contain any asbestos-containing materials. If the
foregoing representation and warranty is incorrect, then Landlord shall pay to
Tenant all additional costs incurred by Tenant in constructing alterations,
additions and improvements which Tenant incurred because the Building Shell was
not constructed in compliance with Law or contained asbestos-containing
materials.

     2. Substantial Completion. "Substantial completion" shall occur when the
        ----------------------   ----------------------
Improvements are substantially completed as certified by the architect preparing
the Shell Plans utilizing AIA document G704, Certificate of Substantial
Completion. Substantial Completion shall have occurred even though minor details
of construction, decoration, landscaping, and mechanical adjustments remain to
be completed by Landlord. When the Certificate of Substantial Completion is
issued, Landlord and the architect shall prepare a punch list of incomplete,
minor, detail items and Landlord shall use all reasonable efforts to complete
such items within 30 days after the Certificate of Substantial Completion is
issued, except as to such items that, by their nature, will take a longer period
to complete as set forth in the punch list. The "Target Date" for Substantial
                                                 -----------
Completion of the Improvements is February 1, 1998. If the actual date of
Substantial Completion is delayed beyond the Target Date because of events
beyond Landlord's reasonable control, including matters of the type described in
Section 23.(c), then Landlord shall have no liability therefor and the date for
Substantial Completion shall be extended by the period of any such delay. If
Substantial Completion is delayed because of any acts of a Tenant Party, then
the Commencement Date shall not be extended, but rather shall start on the date
on which it would have occurred but for such event. Except if Tenant terminates
this Lease under Section 1.(b), this Lease shall remain in full effect
notwithstanding any delay in Substantial Completion.

     3. Early Entry by Tenant. Tenant may enter the Shell Building before
        ---------------------
Substantial Completion with Landlord's prior consent (which shall not be
unreasonably withheld) to perform work therein, provided that (a) Landlord is
given prior written notice of any such entry, (b) such entry shall be
coordinated with Landlord and shall not interfere with Landlord's work, (c)
Tenant shall deliver to Landlord evidence that the insurance required under
Section 9 of this Lease has been

                                      B-1
<PAGE>

obtained, and (d) Tenant shall pay all utility charges reasonably allocable to
Tenant by Landlord in connection with such early entry. Tenant shall conduct its
activities therein so as not to interfere with Landlord's construction
activities, and shall do so at its risk and expense. If, in Landlord's judgment,
Tenant's activities therein interfere with Land1ord's construction activities,
Landlord may terminate Tenant's right to enter the Premises before Substantial
Completion. After Substantial Completion, Tenant may enter into the Premises to
construct and install the initial tenant improvements therein. Any such entry
shall be on the terms of this Lease, but no rent shall accrue in respect of Base
Rent or, except as provided above with respect to utilities, Operating Expenses
during the period that Tenant so enters the Premises before the Commencement
Date.

                                      B-2

<PAGE>

                                   EXHIBIT C
                                   ---------

                                EXTENSION OPTIONS

     1.   Option. Provided no Event of Default exists when Tenant delivers such
          ------
notice, Tenant may renew this Lease as to all of the Premises for two additional
period of five years each on the same terms provided in this Lease (except as
set forth below). On or before the commencement date of the extended Term in
question, Landlord and Tenant shall execute an amendment to this Lease extending
the Term on the same terms provided in this Lease, except as follow:

          (a) The Base Rent payable for each month during the extended Term in
question shall be the Fair Market Rental Rate determined in accordance with
paragraph 2 below;

          (b) Tenant shall have no further renewal options unless expressly
granted by Landlord in writing (other than those that have not been exercised
hereunder); and

          (c) Landlord shall lease to Tenant the Premises in their then-current
condition, and Landlord shall not provide to Tenant any allowances (e.g., moving
allowance, construction allowance, and the like) or other tenant inducements.

     Tenant's rights under this Exhibit shall terminate if (1) this Lease
expires or is cancelled or this Lease or Tenant's right to possession of the
Premises is terminated or (2) Tenant fails timely to exercise its option under
this Exhibit, time being of the essence with respect to Tenant's exercise
thereof. Tenant's rights under this Exhibit are personal to Tenant and may only
be exercised by Tenant or a Permitted Transferee occupying the entire Premises
at the time the option provided herein is exercised.

     2.   Exercise of Option. Tenant shall elect whether to extend the Term by
          ------------------
delivering to Landlord written notice thereof (the "Election Notice") not
                                                    ---------------
sooner than 15 nor later than 9 months before the expiration of the Term. If
Tenant fails to deliver the Election Notice at least 9 months before the end of
the Term, Tenant's rights under this Exhibit shall terminate; time being of the
essence with respect to such delivery. Within 30 days after Landlord receives
the Election Notice, Landlord shall deliver to Tenant its assessment of the
Fair Market Rental Rate ("Landlord's Assessment"). If Tenant disagrees with
                          ---------------------
Landlord's Assessment, it shall deliver to Landlord written notice thereof (an
"Objection Notice") within 30 days after Landlord delivers to Tenant Landlord's
 ----------------
Assessment; otherwise, Landlord's Assessment shall be the Base Rent for the
extended Term. If Tenant timely delivers an Objection Notice, Landlord and
Tenant shall meet to attempt to determine the prevailing rental rate for the
extended Term. If Tenant and Landlord are unable to agree on such prevailing
rental rate within 15 days after Tenant delivers to Landlord the Objection
Notice, Landlord and Tenant shall jointly appoint an independent real estate
appraiser with at least five-years' commercial real estate experience in the
vicinity of the Premises and submit to the appraiser its assessment of the
prevailing rental rate for the extended Term, together with the data used to
support such assessment. If Landlord and Tenant are unable to agree on an
appraiser within five days after such 15-day period, then either party may
request that the Dallas office of the American

                                       C-1
<PAGE>

Arbitration Association appoint such appraiser, which appointment shall be
binding on Landlord and Tenant. Within 20 days after its selection, the
appraiser shall select the assessment closest to his determination of the Fair
Market Rental Rate for the extended Term, which assessment shall be the Base
Rent for the extended Term. Landlord and Tenant shall share equally the cost of
the appraiser. The term "Fair Market Rental Rate" shall mean the market rental
                         -----------------------
rate for the time period such determination is being made for space in
comparable office/warehouse/research/manufacturing buildings in the vicinity of
the Building of comparable condition for space of equivalent quality, size,
utility, and location. Such determination shall take into account all relevant
factors, including length of term, credit standing of Tenant, market concessions
and other factors (but shall not include the value of then-existing improvements
that Tenant is entitled to remove at the end of the Term).

                                      C-2

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00021-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00021-of-00352.parquet"}]]