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                                                                    EXHIBIT 10.4


                               AGREEMENT OF SALE

      AGREEMENT OF SALE (this "Agreement"), dated as of August 28, 2002, between
KULLER ROAD REALTY HOLDINGS, L.L.C., a New Jersey limited liability company
("Seller") and KEYSTONE OPERATING PARTNERSHIP, LP, a Delaware limited
partnership ("Purchaser").

                              Preliminary Statement

      Seller is the owner in fee simple of the lands described on Exhibit A
annexed hereto (the "Lands"), (b) the buildings and other improvements presently
located on such Lands (the "Improvements"), (c) all fixtures, equipment and
machinery on such Lands and in the Improvements used in connection with the
ownership, operation, maintenance and repair thereof but excluding all trade
fixtures and personal property owned by the existing tenant (the "Personal
Property"), (d) the rights, as landlord, under the Leases (as herein defined),
including all rights under any guarantees thereof and any security given for the
performance of the tenants' obligations under such Leases and (e) all easements,
licenses, rights (including any development rights) and appurtenances relating
to the Lands and the Improvements (the "Rights").

      Seller desires to sell, convey, transfer and assign to Purchaser, and
Purchaser desires to acquire from Seller, subject to the terms and conditions of
this Agreement, the Lands, the Improvements, the Personal Property, the Leases
and the Rights and certain other property herein described (all such property
intended to be sold, conveyed, transferred or assigned by Seller to Purchaser
being herein called the "Property").

      NOW, THEREFORE, in consideration of the mutual agreements contained
herein, and other good and valuable consideration, the receipt and sufficiency
of which are hereby acknowledged, and intending to be legally bound, the parties
hereto agree as follows:

                                    ARTICLE 1

                            Definitions; Construction

      1.1 Definitions. As used in this Agreement, the following terms have the
following respective meanings:

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            "Agreement" has the meaning specified in the initial paragraph
            hereof.

            "Broker" means Leo Josephs & Company, Inc.

            "Brokerage Contracts" means all contracts pursuant to which a
            commission or payment is required to be made as a result of the
            leasing of the Property prior to the Closing Date.

            "Closing Date" has the meaning specified in Section 9.3.

            "Condemnation Parcel" means that portion of the Land identified on
            Exhibit U annexed hereto, it being agreed that the portion of the
            Land shown on Exhibit U is not the exact depiction of the
            Condemnation Parcel but rather the outer limits of what may be
            taken.

            "Confidential Information" means any proprietary information
            concerning the Property provided to Purchaser by Seller, excluding
            information that is available to the public or from sources other
            than a Seller.

            "Contracts" means all service, management, supply contracts, and
            other contracts affecting the Property, excluding Brokerage
            Contracts, Guarantees and Warranties.

            "DEP" means the Department of Environmental Protection of the State
            of New Jersey.

            "Deposit" means the amount paid by Purchaser to the Escrow Agent
            pursuant to clause (a) of Section 2.3 and includes all interest
            earned thereon.

            "Due Diligence Period" means a period expiring August 30, 2002.

            "Escrow Agent" means the Title Insurer, or any substitute escrow
            agent appointed hereunder.

            "Guarantees and Warranties" means any guaranty or warranty from any
            construction manager, contractor,

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            subcontractor, material supplier or vendor relating to any of the
            Improvements.

            "Hazardous Substance" means any substance, chemical, pollutant or
            waste that is listed as hazardous, toxic or dangerous under any
            applicable federal, state, county or local statute, rule,
            regulation, ordinance or order.

            "Improvements" has the meaning specified in the Preliminary
            Statement.

            "Kraft Agreement" has the meaning specified in Section 2.1.

            "Lands" has the meaning specified in the Preliminary Statement and
            shall include all right, title and interest of Seller in and to any
            easements and appurtenances.

            "Leases" means, collectively, (a) Lease dated as of August 17, 2001
            between Seller, as landlord, and APX Central, Inc., as tenant and
            (b) Lease dated as of May 11, 2000 between Seller, as landlord, and
            Benjamin Moore & Co., as tenant.

            "Lease Transaction" shall mean any of the following actions: (a) the
            execution of any new lease; (b) the renewal or material modification
            of any of the Leases, or the consent to any assignment of or
            subletting under any of the Leases, other than any renewal,
            expansion, assignment or subletting that must be entered into or
            approved under the terms of the Leases; or (c) the termination of
            any of the Leases.

            "Legal Requirements" means all laws, statutes, codes, ordinances,
            orders, regulations and requirements of all federal, state, county
            and municipal governments, departments, boards, authorities,
            agencies, officials and officers.

            "NJ Transit" means the New Jersey Transit Corporation, its
            successors and assigns.

            "Other Agreement" means the Agreement of Sale dated March 1, 2002
            among Interstate 78 Office Park, Ltd.,

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            Fin Associates Limited Partnership, New York Distribution Center,
            L.P., Raritan Building Associates Limited Partnership, 191 Talmadge
            Road Realty Holdings, L.P., Wedgewood Plaza, L.P., Carlstadt
            Building Realty Holdings, L.P., and Carlstadt Associates, Ltd., as
            sellers, and Keystone New Jersey Associates, LLC, as purchaser, as
            amended.

            "Permitted Exceptions" has the meaning specified in Section 3.1.

            "Personal Property" has the meaning specified in the Preliminary
            Statement.

            "Property" has the meaning specified in the Preliminary Statement.

            "Purchase Price" means the aggregate purchase price for the Property
            specified in Section 2.2, as adjusted in accordance with any
            provision of this Agreement permitting such adjustment.

            "Purchaser" has the meaning specified in the initial paragraph of
            this Agreement and includes any assignee of Purchaser's right, title
            and interest under this Agreement.

            "Purchaser Default" has the meaning specified in Section 11.1.

            "Reciprocal Easement Agreements" means any reciprocal easement
            agreement, declaration of covenants, restriction, easement, common
            area agreement, shared maintenance agreement, common use agreement
            or any similar agreement which benefit or burden the Lands and other
            adjacent real property.

            "Restoration" means the repair and replacement of the Improvements
            or Personal Property substantially to the same condition as existed
            prior to any damage or destruction.

            "Rights" has the meaning specified in the Preliminary Statement.

            "Seller" has the meaning specified in the initial paragraph of this
            Agreement.

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            "Seller Default" has the meaning specified in Section 11.2.

            "Threatened Condemnation" means the threatened taking by NJ Transit
            of approximately 2.5 acres of land comprising the Condemnation
            Parcel.

            "Title Insurer" means Chicago Title Insurance Company.

            "Title Objection" has the meaning specified in Section 3.3.

            "Voluntary Encumbrance" means any (a) mortgage or deed of trust, (b)
            mechanics' or materialmens' liens, (c) liens for unpaid taxes,
            assessments, utility charges or other governmental impositions, (d)
            any other lien or encumbrance granted, assumed or suffered to exist
            securing the repayment of money or the performance of an obligation
            and (e) any encumbrance, including a lease, easement, license,
            covenant or restriction, granted by Seller after the date hereof.

      1.2 Drafting Ambiguities; Interpretation. In interpreting any provision of
this Agreement, no weight shall be given to, nor shall any construction or
interpretation be influenced by, the fact that counsel for one of the parties
drafted this Agreement, each party recognizing that it and its counsel have had
an opportunity to review this Agreement and have contributed to the final form
of same. Unless otherwise specified (a) whenever the singular number is used in
this Agreement, the same shall include the plural, and the plural shall include
the singular, (b) the words "consent" or "approve" or words of similar import,
mean the prior written consent or approval of Seller or Purchaser, (c) the words
"include" and "including", and words of similar import, shall be deemed to be
followed by the words "without limitation" and (d) the Exhibits to this
Agreement are incorporated herein by reference.

                                    ARTICLE 2

          SALE OF PROPERTY; PURCHASE PRICE; PURCHASE PRICE ADJUSTMENTS;
                             ESCROWS; PAYMENT TERMS

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      2.1 Sale of Property. Seller hereby agrees to sell, convey, transfer and
assign to Purchaser, and Purchaser hereby agrees to purchase and acquire from
Seller, the Property upon the terms and conditions herein contained. The
conveyance shall include all right title and interest of Seller in and to (a)
all licenses, permits and other authorizations for the use, operation,
maintenance, ownership and development of the Property, (b) all plans,
specifications, shop drawings, operating manuals and other technical data
relating to the Improvements and the Personal Property, (c) all software and
security codes relating to the operation of the Improvements and the Personal
Property, (e) all rights under Guarantees and Warranties, and (f) all right,
title and interest of Seller under that certain Environmental Remediation And
Post-Closing Access Agreement dated as of August 31, 2000 between Seller and
Kraft Foods, Inc (the "Kraft Agreement"). Nothing contained herein shall be
deemed an assignment or transfer to Purchaser of any rights or claims being
asserted by Seller and Kraft Foods, Inc. against Allied-Signal, Inc. and Allied
Signal Commercial Roofing Systems, Inc., in proceedings pending in the Superior
Court of New Jersey, Morris County, Law Division, in case bearing docket number
MRSL-3024-00 or to any escrow being held in connection with the roof work
described in such litigation, it being agreed that all such claims shall remain
the property of Seller and that Purchaser shall have no interest in any such
escrow. Purchaser agrees to execute any documents reasonably requested by Seller
for the purpose of assigning to Seller the right to all damage claims against
Allied-Signal, Inc. and Allied Signal Commercial Roofing Systems, Inc., or for
the purpose of permitting Seller to settle such claims, including a release of
other parties involved in the litigation, provided (a) Purchaser shall not be
obligated to incur any cost or liability in connection therewith or release any
claims not now asserted in the litigation and (b) Purchaser shall not be
obligated to release any claims to repair water leakage under the roof warranty.

      2.2 Purchase Price. The aggregate purchase price (the "Purchase Price")
for the Property is Twenty Million Five Hundred Thousand Dollars ($20,500,000),
subject to the adjustments provided herein, provided that if the closing occurs
under the Other Agreement, the Purchase Price shall be Twenty One Million
Dollars ($21,000,000).

      2.3 Payment Terms. The Purchase Price shall be payable as follows:

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            (a) within two (2) business days after the expiration of the Due
            Diligence Period, time being of the essence and such payment being a
            condition to the effectiveness of this Agreement, if Purchaser does
            not terminate this Agreement, the sum of $250,000 shall be paid by
            Purchaser to the Escrow Agent, at the option of Purchaser, by check
            (subject to collection) or by wire transfer;

            (b) upon closing of title, the balance of the Purchase Price, plus
            or minus any net closing adjustments, shall be paid by wire transfer
            of immediately available funds to Seller or its designee; and

            (c) upon the closing under the Other Agreement, the sum of $500,000
            shall be paid by wire transfer of immediately available funds to
            Seller or its designee.

      2.4 Terms of Escrow.

            (a) The Deposit shall be held by Escrow Agent in escrow in a JP
Morgan Prime Money Market Fund. Any interest accrued on the Deposit shall be
paid to whichever party is entitled to the Deposit in accordance with the
provisions of this Agreement, provided that if this transaction closes, fifty
percent (50%) of the interest shall be paid to Seller and fifty percent (50%) of
the interest shall be paid to Purchaser. The Deposit shall be held and disbursed
by Escrow Agent in the following manner:

                        (i) to Seller upon consummation of the closing; or

                        (ii) to Seller upon receipt of written demand therefor,
                        stating that Purchaser has defaulted in the performance
                        of Purchaser's obligations under this Agreement beyond
                        any applicable cure period and the facts and
                        circumstances underlying such default; provided,
                        however, that Escrow Agent shall not honor such demand
                        until at least ten (10) days after it has sent a copy of
                        such demand to Purchaser, nor thereafter if Escrow Agent
                        shall have received written notice of objection from
                        Purchaser in accordance with

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                        the provisions of clause (b) of this Section 2.4; or

                        (iii) to Purchaser upon receipt of written demand
                        therefor, stating that either (x) this Agreement has
                        been terminated pursuant to a provision hereof which
                        states that Purchaser is entitled to the Deposit upon
                        termination, and certifying the basis for such
                        termination, or (y) Seller has defaulted in performance
                        of its obligations under this Agreement and the facts
                        and circumstances underlying such default; provided,
                        however, that, except in the case of a termination by
                        Purchaser pursuant to Section 4.1, Escrow Agent shall
                        not honor such demand until at least ten (10) days after
                        it has sent a copy of such demand to Seller, nor
                        thereafter if Escrow Agent shall have received written
                        notice of objection from Seller in accordance with the
                        provisions of clause (b) of this Section 2.4. In the
                        event of a termination by Purchaser pursuant to Section
                        4.1, Escrow Agent shall promptly remit the Deposit to
                        Purchaser.

            (b) Upon receipt of written demand for the Deposit by Purchaser or
Seller pursuant to clauses (ii) or (iii) of Section 2.4(a), Escrow Agent shall
promptly send a copy thereof to the other party. Except in the case of a
termination pursuant to Section 4.1, the other party shall have the right to
object to the delivery of the Deposit by sending written notice of such
objection to Escrow Agent within the five (5) days after Escrow Agent delivers a
copy of the written demand to the objecting party but not thereafter. Such
notice shall set forth the basis for objecting to the delivery of the Deposit.
Upon receipt of such notice, Escrow Agent shall promptly send a copy thereof to
the party who made the written demand.

            (c) In the event of any dispute between the parties regarding the
Deposit, Escrow Agent, at its option, may disregard all instructions received
and either (i) hold the Deposit until the dispute is mutually resolved and
Escrow Agent is advised of this fact in writing by both Seller and Purchaser, or
Escrow Agent is otherwise instructed by a final unappealable

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judgment of a court of competent jurisdiction, or (ii) deposit the Deposit with
a court of competent jurisdiction (whereupon Escrow Agent shall be released and
relieved of any and all liability and obligations hereunder from and after the
date of such deposit).

            (d) In the event Escrow Agent shall be uncertain as to its duties or
rights hereunder or shall receive conflicting instructions, claims or demands
from the parties hereto, or instructions which conflict with any of the
provisions of this Agreement, Escrow Agent shall be entitled (but not obligated)
to refrain from taking any action other than to keep safely the Deposit until
Escrow Agent shall be instructed otherwise in writing signed by both Seller and
Purchaser, or by final judgment of a court of competent jurisdiction.

            (e) Escrow Agent may rely upon, and shall be protected in acting or
refraining from acting upon, any written notice, instruction or request
furnished to it hereunder and believed by it to be genuine and to have been
signed or presented by the proper party or parties, provided that any
modification of this Agreement shall be signed by Escrow Agent, Purchaser and
Seller.

            (f) Seller and Purchaser shall jointly and severally hold Escrow
Agent harmless against any loss, damage, liability or expense incurred by Escrow
Agent not caused by its willful misconduct or gross negligence, arising out of
or in connection with its entering into this Agreement and the carrying out of
its duties hereunder, including the reasonable costs and expenses of defending
itself against any claim of liability or participating in any legal proceeding.
Escrow Agent may consult with counsel of its choice, and shall have full and
complete authorization and protection for any action taken or suffered by it
hereunder in good faith and in accordance with the opinion of such counsel.

            (g) Seller and Purchaser shall share equally the responsibility for
reimbursement to Escrow Agent of all out-of-pocket expenses, disbursements and
advances (including reasonable attorneys' fees)

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incurred or made by Escrow Agent in connection with the carrying out of its
duties hereunder.

            (h) Escrow Agent's agreements and obligations hereunder shall
terminate and Escrow Agent shall be discharged from further duties and
obligations hereunder upon final payment of the Deposit in accordance with the
terms of this Agreement.

                                    ARTICLE 3

                                TITLE TO PROPERTY

      3.1 Title to Lands and Improvements. Title to the Lands and Improvements
shall be good, marketable and insurable at regular rates by the Title Insurer,
subject to (a) the exceptions listed on Exhibit B annexed hereto, (b) the Leases
and (c) any exceptions to which Purchaser does not object pursuant to Section
3.3 (the "Permitted Exceptions").

      3.2 Title to Other Property. Title to the Personal Property and all other
property intended to be conveyed or assigned hereunder to Purchaser shall be
good and valid, subject to no encumbrances or security interests.

      3.3 Title Defects. Purchaser shall furnish to Seller within three (3)
calendar days from the date hereof a copy of title commitments with respect to
the Property prepared by the Title Insurer and a copy of any other searches
conducted with respect to the Property, together with a statement specifying any
objections to title or survey matters ("Title Objection"). Seller shall cure any
Voluntary Encumbrance prior to the Closing Date, provided Seller shall not be
obligated to expend more than the net Purchase Price (after closing adjustments)
to remove any Voluntary Encumbrance from the Property. If Seller does not agree
to remove any Title Objection (excluding a Voluntary Encumbrance) within two (2)
business days after receipt of notice of the Title Objection, Purchaser shall
have the option, to be exercised within two (2) business days after receipt of
such notice from Seller, to either (a) waive the Title Objection which is not
removed and close title without abatement or reduction of the Purchase Price or
(b) terminate this Agreement, whereupon, the Deposit shall be returned to
Purchaser, and upon such return, this Agreement and all rights and obligations
of the respective parties hereunder shall be null and void. The failure or
refusal of Seller to remove a Voluntary Encumbrance to the extent provided above
shall constitute a default hereunder.

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      3.4 Right to Pay Off Monetary Encumbrances. Seller shall have the right to
pay off any monetary encumbrances against the Property on the Closing Date out
of the cash then payable provided recordable instruments of release or discharge
of such encumbrances in form and substance satisfactory to counsel for Purchaser
and the Title Insurer are then delivered to Purchaser.

                                    ARTICLE 4

                               TERMINATION RIGHTS

      4.1 Due Diligence Period; Termination. Purchaser shall have the right,
during the Due Diligence Period, to inspect the Property and to investigate
existing zoning, the Leases, the physical and environmental condition of the
Property, the adequacy of existing utilities, the plans and specifications for
the Improvements, surveys, appraisals, service contracts, real estate taxes,
economic feasibility and any other factors Purchaser deems relevant in
determining whether to purchase the Property. If for any or no reason Purchaser
is not satisfied with the results of its investigations, Purchaser may terminate
this Agreement on notice to Seller and Escrow Agent given within the Due
Diligence Period, the time for giving such notice being of the essence. In the
event of such termination, the Deposit shall be returned to Purchaser, whereupon
this Agreement and all rights and obligations of the respective parties
hereunder shall be null and void. If Purchaser does not elect to terminate this
Agreement pursuant to this Section 4.1 within the Due Diligence Period,
Purchaser shall conclusively be deemed to have waived its right of termination
under this Section 4.1.

      4.2 Right of Entry. Purchaser and its agents, employees and consultants
shall, subject to the rights of the existing tenant, have access to the Lands
and Improvements from time to time, upon reasonable notice, prior to the Closing
Date for the purpose of inspecting the Property and undertaking tests and
studies thereof, provided (a) Purchaser promptly repairs any damage caused by
such entry, (b) Purchaser restores the Property to the condition that existed
prior to such entry and (c) Purchaser does not unreasonably interfere with the
rights of the existing tenant. Purchaser shall hold and save Seller harmless
from and against any and all loss, cost, damage, injury or expense arising out
of the activities of Purchaser, its agents, employees and consultants, relating
to any such entry, provided that Purchaser shall not be liable for (a) the
discovery of any preexisting condition, (b) any claims of diminution in the
value

<PAGE>

of any Property as a consequence of the results revealed by any such
investigations or testing or (c) the acts of Seller or its agents or
representatives. Prior to conducting any intrusive testing on any Property,
Purchaser shall furnish to the Seller evidence that Purchaser has procured
comprehensive general liability insurance from an insurer authorized to do
business in the State of New Jersey, which is reasonably acceptable to Seller,
insuring Seller against claims for bodily injury, death or damage to property in
single limit amount of not less than $2,000,000, naming Seller as an additional
insured. The indemnification provision contained in this Section 4.2 shall
survive the termination of this Agreement and the closing of title.

      4.3 Availability of Documents and Inquiries. Seller represents and
warrants that, prior to the date of this Agreement, Seller has furnished to
Purchaser copies of the title policies in it is possession relating to the
Property, copies of existing surveys in its possession, copies of the Leases and
copies of the most current environmental reports in its possession for the
Property. Seller will permit Purchaser to review and copy tenant files and
operating expense information, and to the extent in the possession of Seller,
plans and specifications (including as built plans and shop drawings),
certificates of occupancy, engineering data and reports and soils investigation
reports. Seller shall also promptly respond to any inquiries of Purchaser with
respect to the ownership, operation, maintenance or repair of the Property.
Purchaser, personally or through its authorized representatives or agents, shall
be entitled to interview the tenant.

      4.4 Audits. Purchaser shall also have the right at any time prior to the
Closing Date, at Purchaser's expense, to have independent accountants selected
by Purchaser prepare audited financial statements with respect to the Property
from any books and records that are in the possession of Seller. Seller agrees
to cooperate in the conduct of any such audit, to make its books and records
available and to furnish to such accounting firm such information as is
customarily provided in connection with similar audits.

      4.5 Termination of Contracts. Effective as of the Closing Date, Seller
shall terminate all Contracts and all exclusive listing agreements at no cost to
Purchaser.

      4.6 Brokerage Obligations. On the Closing Date, Purchaser shall assume the
obligations of Seller under the Brokerage Contracts identified on Exhibit C
annexed hereto, but

<PAGE>

only to the extent of the occurrence of any event after the Closing Date which
would give rise to a commission liability under the Brokerage Contracts,
including, without limitation, commissions that become due and payable
thereunder as a result of the exercise by the existing tenant of an extension or
expansion right after the Closing Date.

      4.7 Confidential Information. Prior to the closing, Purchaser shall use
the Confidential Information only for purposes of evaluating the Property in
connection with its potential purchase thereof (and if this transaction closes,
in connection with the ownership and operation of the Property). Notwithstanding
the foregoing, Purchaser may disclose the Confidential Information to legal
counsel, accountants, lenders, potential investors, regulatory authorities and
consultants and Purchaser may disclose the Confidential Information to the
extent that such disclosure is required by law or court order or by discovery
rules in any legal proceeding, provided Purchaser gives Seller prior notice
thereof. If this Agreement is terminated by Purchaser prior to closing,
Purchaser shall return the Confidential Information to Seller.

                                    ARTICLE 5

                    REPRESENTATIONS AND WARRANTIES OF SELLER

      5.1 Representations and Warranties. As an inducement to Purchaser to enter
into this Agreement, Seller represents and warrants to Purchaser that:

            (a) Seller is duly organized and validly existing under the laws of
            the State of its formation, is in good standing both in the State of
            its formation and in the State of New Jersey, has the power and
            authority to enter into this Agreement and to consummate the
            transactions herein contemplated, and the execution and delivery
            hereof and the performance by Seller of its obligations hereunder
            will not violate or constitute an event of default under the terms
            or provisions of any agreement, document or other instrument to
            which such Seller is a party or by which it or the Property is
            bound;

            (b) the execution, delivery and performance of this Agreement by
            Seller and the consummation of the transactions contemplated hereby
            in the manner contemplated herein will not violate any provision of

<PAGE>

            law, statute, rule or regulation to which Seller or the Property is
            subject or violate any judgment, order, writ, injunction or decree
            of any court applicable to Seller or the Property;

            (c) all proceedings required to be taken by or on behalf of Seller
            to authorize it to make, deliver and carry out the terms of this
            Agreement have been or will be duly and properly taken and this
            Agreement is the legal, valid and binding obligation of Seller
            enforceable in accordance with its terms;

            (d) Seller has not executed and has no actual knowledge of any other
            agreement of sale, option agreement, right of first refusal or right
            of first offer with respect to the Property and neither of the
            tenants under the Leases has an option, right of first refusal or
            right of first offer with respect to the Property;

            (e) (i)the Leases are the only leases or possessory rights currently
            affecting or relating to the Property; (ii) the copy of each of the
            Leases furnished or to be furnished is a true, correct and complete
            copy thereof; (iii) neither of the Leases has been modified or
            amended; (iv) each of the Leases is in full force and effect; (v) no
            rent or additional rent has been paid under the Leases in advance of
            the applicable due date; (vi) except as indicated on Exhibit D
            annexed hereto, there is no default, or alleged default, by landlord
            or, to the best knowledge of Seller, any default by either tenant in
            the keeping, observance or performance of any covenant, agreement,
            term, provision or condition contained in the Leases; (vii) neither
            of the tenants under the Leases has any offsets, deductions or
            defenses to the payment of any rent or additional rent under the
            Leases; (viii) Seller has received and holds only the security
            deposit in respect of the Leases identified on Exhibit E; and the
            information contained on Exhibits D, E and J is true, correct and
            complete; (ix) to the best knowledge of Seller, neither tenant under
            the Leases has filed and does not intend to file any bankruptcy or
            insolvency proceedings; (x) there are no outstanding tenant
            improvement allowances, moving allowances or other inducements or
            concessions owed to either tenant


<PAGE>

            under the Leases; (xi) neither of the tenants under the Leases has
            overpaid any rent or additional rent, except additional rent subject
            to reconciliation under the Leases; and (xii) neither tenant under
            the Leases is currently auditing the operating expenses of Seller
            and Seller has not received notice that either tenant intends to
            conduct such an audit.

            (f) (i) the agreements identified on Exhibit C annexed hereto are
            the only Brokerage Contracts executed by Seller or of which Seller
            has knowledge in connection with the Property; (ii) the copies of
            the Brokerage Contracts furnished or to be furnished to Purchaser
            are true, correct and complete copies thereof; (iii) except as
            indicated on Exhibit C annexed hereto, Seller has paid all
            commissions due and payable thereunder with respect to the term of
            the Leases which is now in effect and any pre-existing term; and
            (iv) except as provided on Exhibit C, there is no default, or
            alleged default, by Seller, or the to best knowledge of Seller, any
            default by any other party under any of the Brokerage Contracts;

            (g) except as listed on Exhibit F annexed hereto, there are no
            proceedings at law or in equity (including proceedings contesting
            any tax or assessment) before any court, grand jury, administrative
            agency or other investigative agency, bureau or instrumentality of
            any kind pending or, to the best of Seller's knowledge, threatened,
            against or affecting Seller or the Property that (i) involve the
            validity or enforceability of this Agreement or any other instrument
            or document to be delivered by Seller pursuant hereto, (ii) enjoin
            or prevent or threaten to enjoin or prevent the performance of the
            obligations of any Seller hereunder or (iii) relate specifically to
            the Property or the title thereto;

            (h) attached hereto as Exhibit G is a true and complete list of all
            Personal Property included in this transaction;

            (i) no consent, authorization, license, permit, registration or
            approval of, or exemption or other action by, any governmental or
            public body, commission or authority is required in connection

<PAGE>

            with the execution, delivery and performance by any Seller of this
            Agreement;

            (j) Seller is not a "foreign person" under the Foreign Investment in
            Real Property Tax Act of 1980 and upon consummation of the
            transaction contemplated hereby, Purchaser will not be required to
            withhold from the Purchase Price any withholding tax;

            (k) Seller has not received any notice from any governmental
            authority having jurisdiction over the Property that any Property
            does not comply with any applicable Legal Requirement or with any
            requirement of any insurer or rating bureau;

            (l) except as specified in the documents identified on Exhibit H
            annexed hereto, (i) to the best knowledge of Seller, there are no
            Hazardous Substances on, in or under the Property in violation of
            applicable Legal Requirements; (ii) there is no order, judgement or
            decree outstanding requiring any Seller or any other party to
            undertake any remedial activity on the Property; (iii) there is no
            ongoing remediation on the Property; and (iv) to the best knowledge
            of Seller, there are no underground storage tanks on the Property
            and, except as disclosed on Exhibit I annexed hereto, no storage
            tanks have been removed from the Property;

            (m) to the best knowledge of Seller, attached hereto as Exhibit J is
            a true and correct copy of the rent roll for the Property
            identifying all rent and additional rent actually being collected
            under the Leases;

            (n) (i) attached hereto as Exhibit K is a list of all permits,
            licenses and approvals obtained by Seller relating to the ownership
            and operation of the Property; (ii) such permits, licenses and
            approvals are in full force and effect and free from material
            default; and (iii) Seller has not received any notice that any
            permit, license or approval not listed on Exhibit K is required in
            connection with the ownership or operation of the Property;

<PAGE>

            (o) (i) attached hereto as Exhibit L is a list of all Guarantees and
            Warranties relating to the Property; (ii) such Guarantees and
            Warranties are in full force and effect and (iii) there are no
            defaults or alleged defaults by any party thereunder;

            (p) all information with respect to the operating expenses of the
            Property furnished or to be furnished by Seller to Purchaser with
            respect to the Property is true, correct and complete;

            (q) to the actual knowledge of Seller, except as disclosed in the
            environmental reports identified on Exhibit H, there is no
            environmental condition on the Property that materially affects the
            value or use of the Property;

            (r) there are no union or collective bargaining agreements relating
            to the Property or any person employed by Seller in connection with
            the Property;

            (s) the Kraft Agreement has not been amended, modified or
            terminated.

                  5.2 Limitation on Representations and Warranties. PURCHASER
ACKNOWLEDGES AND AGREES THAT, EXCEPT AS EXPRESSLY SET FORTH IN THIS AGREEMENT,
NEITHER SELLER, NOR ANY AGENT OR REPRESENTATIVE OF SELLER, HAS MADE, ANY EXPRESS
OR IMPLIED REPRESENTATIONS, WARRANTIES, COVENANTS, AGREEMENTS, OBLIGATIONS,
GUARANTEES, STATEMENTS, INFORMATION OR INDUCEMENTS PERTAINING TO THE PROPERTY,
TITLE TO THE PROPERTY, THE PHYSICAL CONDITION THEREOF, THE FITNESS AND QUALITY
THEREOF, THE VALUE AND PROFITABILITY THEREOF, OR ANY OTHER MATTER WITH RESPECT
THERETO. PURCHASER ACKNOWLEDGES THAT AS OF THE EXPIRATION OF THE DUE DILGENCE
PERIOD IT WILL HAVE HAD SUCH ACCESS TO THE PROPERTY AND SUCH OTHER MATTERS AND
TO INFORMATION AND DATA RELATING TO ALL OF SAME AS PURCHASER HAS CONSIDERED
NECESSARY, PRUDENT, APPROPRIATE OR DESIRABLE FOR THE PURPOSES OF THIS
TRANSACTION. WITHOUT LIMITING THE FOREGOING, PURCHASER ACKNOWLEDGES AND AGREES
THAT, EXCEPT AS EXPRESSLY SET FORTH IN THIS AGREEMENT, NEITHER SELLER NOR ANY
REPRESENTATIVE OF SELLER IS LIABLE OR RESPONSIBLE FOR OR BOUND IN ANY MANNER BY
(AND PURCHASER HAS NOT RELIED UPON) ANY VERBAL OR WRITTEN OR SUPPLIED
REPRESENTATIONS, WARRANTIES, COVENANTS, AGREEMENTS, OBLIGATIONS, GUARANTEES,
STATEMENTS OR INFORMATION PERTAINING TO THE PROPERTY. PURCHASER ACKNOWLEDGES AND
AGREES THAT, EXCEPT AS OTHERWISE PROVIDED IN THIS AGREEMENT, PURCHASER IS
PURCHASING

<PAGE>

THE PROPERTY, "AS IS" AT THE DATE HEREOF, SUBJECT TO ANY REASONABLE WEAR AND
TEAR BETWEEN THE DATE HEREOF AND THE CLOSING DATE

      5.3 Survival of Seller's Representations and Warranties. The
representations and warranties contained in Section 5.1 are true, accurate and
complete and not misleading in any material respect as of the date hereof and
shall be deemed to be repeated at and as of the Closing Date, and shall be true,
accurate and complete and not misleading in any material respect as of such
date, subject, in each such case, to the discovery of any inaccuracy not caused
by the willful action of Seller arising from any events occurring subsequent to
the date hereof. The representations and warranties in Section 5.1 shall survive
the closing for a period of one (1) year from the Closing Date.

      5.4 Changes to Representations and Warranties. If prior to the closing,
Seller obtains actual knowledge that any representation or warranty of Seller
becomes inaccurate or incomplete in any material respect, Seller shall promptly
give Purchaser notice thereof, describing such inaccuracy and the circumstances
causing such inaccuracy. If Seller does not cure such inaccuracy within ten (10)
calendar days after receipt of such notice, Purchaser shall have the right, at
its option, to terminate this Agreement within twenty (20) days after the giving
of such notice. Upon such termination, the Deposit shall be refunded to
Purchaser, whereupon neither Seller nor Purchaser shall have any further rights
against the other hereunder. If Purchaser fails to give notice of a termination
within such period, unless the inaccuracy was caused by the willful action of
Seller or was inaccurate as of the date hereof, Purchaser shall conclusively be
deemed to have waived its right to terminate this Agreement as a result thereof.
If such inaccuracy was caused by the willful action of Seller or such
representation or warranty was inaccurate as of the date hereof, Purchaser shall
not be deemed to waive its termination right or any other rights under this
Agreement. If, however, Purchaser proceeds to close with knowledge of such
inaccuracy, then Purchaser shall be deemed to have waived same and shall have no
claim on account thereof against Seller.

      5.5 Inaccuracies Discovered by Purchaser. If prior to the closing,
Purchaser shall independently learn of any material inaccuracy in any of the
representations or warranties of Seller, and with actual knowledge of such
inaccuracy elects to consummate the closing, the Purchaser shall be deemed to
have waived the same and shall have no claim on account thereof against Seller.

<PAGE>

                                    ARTICLE 6

                   REPRESENTATIONS AND WARRANTIES OF PURCHASER

      6.1 Representations and Warranties. As an inducement to Seller to enter
into this Agreement, Purchaser represents and warrants that:

            (a) Purchaser is a limited partnership duly organized and validly
            existing under the laws of the State of Delaware, is qualified to
            conduct business in the State of New Jersey, is in good standing,
            has the power and authority to enter into this Agreement and to
            consummate the transactions herein contemplated and the execution
            and delivery hereof and the performance by Purchaser of its
            obligations hereunder will not violate or constitute an event of
            default under the terms or provisions of any agreement, document or
            other instrument to which Purchaser is a party or by which it is
            bound;

            (b) the execution, delivery and performance of this Agreement by
            Purchaser and the consummation of the transactions contemplated
            hereby in the manner contemplated herein will not violate any
            provision of law, statute, rule or regulation to which Purchaser is
            subject or violate any judgment, order, writ, injunction or decree
            of any court applicable to Purchaser; and

            (c) no consent, authorization, license, permit, registration or
            approval of, or exemption or other action by, any governmental or
            public body, commission or authority is required in connection with
            the execution, delivery and performance by Purchaser of this
            Agreement.

      6.2 Survival. The representations and warranties contained in Section 6.1
are true, accurate and complete and not misleading in any material respect as of
the date hereof, shall be deemed to be repeated at and as of the Closing Date
and shall be true, accurate and complete and not misleading in any material
respect as of such date. Each such representation and warranty shall survive the
Closing Date for a period of one (1) year from the Closing Date.

                                    ARTICLE 7

<PAGE>

                         OTHER COVENANTS AND AGREEMENTS

      7.1 No Contracts, Liens or Encumbrances. Seller agrees that it will not
create, suffer or permit to be created, and that it will promptly remove or
discharge, any liens or encumbrances against the Property arising subsequent to
the date of this Agreement and prior to the Closing Date, provided that Seller
shall not be obligated to expend more than the net Purchase Price (after closing
adjustments) to remove any Voluntary Encumbrance. Seller further agrees that,
except as provided in Section 7.5, it will not enter into any contracts or
agreements relating to the Property prior to the Closing Date, including any new
Contracts or Brokerage Contracts.

      7.2 Maintenance of the Property. Seller will cause the Property to be
maintained in substantially the same condition as now maintained, will operate
the Property in substantially the same manner as the Property has heretofore
been operated and will use commercially reasonable efforts to maintain in effect
any Guarantees and Warranties. Seller will cure any violations of applicable
Legal Requirements arising prior to the Closing Date. Seller will not enter into
any construction, management, brokerage, maintenance or service contracts which
would become the obligation of Purchaser; and will promptly inform Purchaser in
writing upon obtaining actual knowledge of any material event adversely
affecting the ownership, use, occupancy, operation or maintenance of the
Property, whether or not insured against.

      7.3 Insurance. Seller will cause the existing fire, extended coverage and
public liability insurance covering the Property to be maintained in full force
and effect as heretofore maintained by it.

      7.4 Performance of Obligations. Seller will promptly (a) comply with all
obligations of the landlord under the Leases, the Reciprocal Easement Agreements
and the Guarantees and Warranties and (b) promptly upon obtaining knowledge
thereof, notify Purchaser of any default by Seller or the tenant under the
Leases or by Seller under any of the Reciprocal Easement Agreements and
Guarantees and Warranties.

      7.5 Leasing. After the date hereof, Seller will not, without the prior
consent of Purchaser, which such consent may be denied by Purchaser for any
reason, enter into any Lease Transaction, except that, without Purchaser's
consent, Seller may renew or extend the Leases, or permit the existing tenants
to

<PAGE>

lease additional space pursuant to the exercise by such tenant of a renewal,
extension or expansion option presently contained in the Leases. Seller will
promptly furnish to Purchaser a copy of any document evidencing a transaction
described above.

      7.6 No Marketing. Seller shall not, directly or indirectly, market the
Property for sale, exchange or other disposition to any third party.

                                    ARTICLE 8

                      DAMAGE, DESTRUCTION AND CONDEMNATION

      8.1 Casualty. The risk of loss or damage to the Property by fire or other
casualty before the delivery of the deed hereunder is assumed by Seller. In the
event of any damage to or destruction of the Property due to fire or any other
cause or hazard, Seller shall promptly give notice thereof to Purchaser
describing such damage and indicating the estimated cost and period required for
Restoration. If the cost of Restoration as estimated by Purchaser in good faith
is in excess of $500,000, or as a result of such damage or destruction a tenant
is permitted to cancel any of the Leases (which right of cancellation is not
waived by the tenant prior to a termination by Purchaser or deemed waived
because the time within which such tenant may cancel has expired), then
Purchaser, upon notice to Seller given within ten (10) days after receipt of
notice of such occurrence, may, at its option, terminate this Agreement,
whereupon the Deposit shall be refunded to Purchaser and neither Seller nor
Purchaser shall have any further rights against the other hereunder. In the
event that the cost of Restoration is less than $500,000 as determined by any of
the architects or contractors set forth on Exhibit M hereto or such other party
approved by Seller and Purchaser, or if in excess thereof and Purchaser does not
elect to terminate this Agreement, Purchaser shall be entitled to a credit on
the Closing Date against the Purchase Price in an amount equal to the cost of
Restoration.

      8.2 Condemnation. (a) The parties acknowledge that Seller has been advised
of the Threatened Condemnation of the Condemnation Parcel by NJ Transit.
Purchaser agrees that it shall have no right to terminate this Agreement because
of the Threatened Condemnation.

      (b) In the event any proceedings or negotiations are instituted which do
or may result in a taking by condemnation or eminent domain of the Property or
any portion thereof, other than

<PAGE>

the Threatened Condemnation of the Condemnation Parcel, Seller shall promptly
notify Purchaser thereof, describing the nature and extent thereof. Purchaser
may, within ten (10) days after receipt of such notice, at its option, terminate
this Agreement, whereupon the Deposit shall be refunded to Purchaser and neither
Seller nor Purchaser shall have any further rights against the other hereunder.
In the event Purchaser does not terminate this Agreement, the sale of the
Property shall be consummated as herein provided and Seller shall assign to
Purchaser on the Closing Date all of its right, title and interest in and to all
awards payable by reason thereof and shall pay over to Purchaser all amounts
theretofore received by Seller in connection with such condemnation or taking.
Seller agrees not to settle or compromise any claim for such award without the
prior written consent of Purchaser. Purchaser shall have the right, at its cost,
to participate in any condemnation proceeding, unless Purchaser terminates this
Agreement.

      8.3 Hazardous Substances. In the event that after Purchaser completes its
environmental audit of the Property and prior to the Closing Date there is a
spill, discharge, release, deposit or emplacement of any Hazardous Substance on
the Property which results in contamination of the Property beyond permitted
governmental tolerances, Seller shall, promptly upon obtaining knowledge
thereof, notify Purchaser of such event, describing the nature and extent
thereof. Purchaser may, within fifteen (15) days after receipt of such notice,
at its option, terminate this Agreement whereupon the Deposit shall be refunded
to Purchaser and neither Seller nor Purchaser shall have any further rights
against the other hereunder. If Purchaser does not so terminate this Agreement,
Purchaser shall be entitled to a credit against the Purchase Price in an amount
equal to the cost to remediate the Property, as estimated in good faith by
Purchaser, provided that in no event shall such credit exceed $500,000. Upon
receipt of such credit, Seller shall have no liability or responsibility for
such remediation of such contamination.

                                    ARTICLE 9

                CONDITIONS PRECEDENT; CLOSING DATE AND DELIVERIES

      9.1 Conditions Precedent to Seller's Obligation to Complete Closing.
Purchaser agrees that Seller's obligation to complete the closing hereunder
shall be subject to the fulfillment, on the Closing Date, of the following
conditions precedent, provided however, that Seller, in its sole discretion, may
elect to waive any thereof:

<PAGE>

            (a)   Purchaser shall pay to Seller the Purchase Price as provided
                  in Article 2;

            (b)   Purchaser shall not be in material default in the performance
                  of its obligations under this Agreement ;

            (c)   the representations and warranties of Purchaser contained in
                  Section 6.1 shall be true, complete and accurate in all
                  material respects; and

            (d)   the closing under the Other Agreement shall have occurred or
                  shall occur simultaneously with the closing of this
                  transaction.

In the event any of the foregoing conditions precedent are not waived by Seller,
Seller shall have the rights and remedies provided in Section 11.3(a) respecting
a Purchaser Default.

      9.2 Conditions Precedent to Purchaser's Obligation to Complete Closing.
Seller agrees that Purchaser's obligation to complete the closing hereunder
shall be subject to the fulfillment, prior to the Closing Date, of the following
conditions precedent, provided however, that Purchaser, in its sole discretion,
may elect to waive any thereof:

            (a) title to the Property shall be as specified in Section 3.1 and
            Section 3.2;

            (b) Seller shall not be in default in the performance of its
            obligations under this Agreement;

            (c) the representations and warranties of Seller contained in
            Section 5.1 shall be true, complete and accurate in all respects;

            (d) on the Closing Date the Title Insurer shall issue to Purchaser
            owner's title insurance policies (Form ALTA 10-17-92) in the amount
            of the Purchase Price insuring good and marketable title to the
            Property in Purchaser subject only to Permitted Exceptions; and

            (e) Seller shall have delivered to Purchaser estoppel certificates
            from the tenants under the Leases, dated not more than thirty (30)
            days prior to

<PAGE>

            the Closing Date, substantially in form annexed hereto as Exhibit N,
            containing no material qualifications, conditions or alleged
            defaults.;

            (f) Seller shall have delivered to Purchaser a "letter of non
            applicability", "de minimus quantity exemption" or "no further
            action letter" from the DEP confirming that the conveyance of the
            Property is not subject to the provisions of the Industrial Site
            Recovery Act of the State of New Jersey or a "no further action
            letter" from the DEP, provided such letter is not conditioned upon
            any use restrictions, administrative or engineering controls or any
            other restriction, including but not limited to, the establishment
            of a classification exception area.

In the event any of the foregoing conditions precedent are not waived by
Purchaser, Purchaser may terminate this Agreement on notice to Seller and Escrow
Agent given at or prior to the Closing Date, the time for giving such notice
being of the essence. In the event of such termination, the Deposit shall be
returned to Purchaser, whereupon this Agreement and all rights and obligations
of the respective parties hereunder shall be null and void. If Purchaser does
not elect to terminate this Agreement pursuant to this Section 9.2 at or prior
to the Closing Date, Purchaser shall conclusively be deemed to have waived its
right of termination under this Section 9.2. Seller agrees to exercise good
faith and commercially reasonable efforts to cause the tenant of the Property to
execute and deliver the documents described in clauses (e) and (f) of this
Section 9.2.

      9.3 Closing Date. The closing of this transaction shall be conducted on
September 6, 2002 at 10:00 A.M. (the "Closing Date"), provided that if Seller is
unable to obtain the documents identified in clause (f) of Section 9.3 by such
date, the Closing Date shall automatically be adjourned to a date that is four
(4) business days after Seller furnishes copies of such documents to Purchaser,
provided further that in no event shall the Closing Date be adjourned beyond
September 30,2002. If the closing does not occur on such date, either party
shall have the right to make time of the essence upon two (2) business days
notice to the other. The closing shall be conducted at the offices of Drinker
Biddle & Shanley, LLP, 500 Campus Drive, Florham Park, New Jersey 07932, or at
such other place as the parties shall elect. Upon the closing, possession of the
Property shall be delivered to

<PAGE>

Purchaser, and Purchaser shall thence have the right to enjoy the rents, issues
and profits therefrom.

      9.4 Documents to be Delivered by Seller. On the Closing Date, Seller shall
deliver to Purchaser the following documents:

            (a) duly executed Deed of Bargain and Sale with Covenant Against
            Grantor's Acts for the Lands and the Improvements in proper
            statutory form for recordation;

            (b) duly executed Bill of Sale for the Personal Property in form
            annexed hereto as Exhibit P;

            (c) all as built plans, specifications and drawings and shop
            drawings and all manuals relating to the maintenance and operation
            of the Property in Seller's possession or control;

            (d) duly executed Affidavit of Title in form annexed hereto as
            Exhibit Q;

            (e) duly executed FIRPTA Affidavit in form of Exhibit R annexed
            hereto;

            (f) all keys to the Improvements in the possession of Seller;

            (g) an original counterpart of the Leases, tenant files and
            correspondence in the possession of Seller;

            (h) originals of all Guarantees and Warranties in the possession or
            control of Seller;

            (i) discharges of all mortgages, security interests, pledges and
            liens affecting the Property;

            (j) notices from Seller to each of the tenants under the Leases
            advising that title to the Lands and the Improvements has been
            conveyed to Purchaser and instructing that all rent and additional
            rent payable under the Leases is to be remitted to Purchaser and
            that all insurance required to be maintained by each such tenant
            under the Leases is to be amended to name Purchaser and its lender
            as a named insured;

<PAGE>

            (k) an estoppel certificate from all parties to any Reciprocal
            Easement Agreement, dated not more than thirty (30) days prior to
            the Closing Date, in form and substance satisfactory to Purchaser;

            (l) an updated rent roll for the Property certified by Seller;

            (m) such other documents and instruments as Purchaser or its Title
            Insurer may reasonably request to perfect title to the Property in
            Purchaser;

            (n) a statement explaining the method of calculating additional rent
            under the Leases;

            (o) any original letters of credit delivered under the Leases as
            security for the performance of the tenant's obligations, together
            with documents in form reasonably satisfactory to Purchaser naming
            Purchaser as the substitute beneficiary thereof;

            (p) evidence that Seller has paid all sums due and payable under the
            Brokerage Contracts; and

            (q) a certificate, dated the Closing Date and signed by a managing
            member of Seller, stating that the representations and warranties
            contained in Section 5.1 are true, correct and complete as of such
            date, except to the extent provided in any notice given to Purchaser
            in accordance with Section 5.4.

      9.5 Documents to be Delivered by Purchaser. On the Closing Date, Purchaser
shall deliver to Seller a certificate, dated as of the Closing Date and signed
by the general partner of Purchaser, stating that the representations and
warranties contained in Section 6.1 are true, correct and complete as of such
date.

      9.6 Documents to be Delivered by Both Parties. On the Closing Date, Seller
and Purchaser shall execute and deliver the following documents:

            (a) duly executed Assignment in form annexed hereto as Exhibit S;

            (b) duly executed Assignments and Assumption of Leases in form
            annexed hereto as Exhibit T;

<PAGE>

            (c) duly executed Assignment and Assumption of any Guarantees and
            Warranties;

            (d) Forms 1099; and

            (e) statements showing all closing prorations.

      9.7 Certificates of Occupancy etc. If any applicable Legal Requirement
requires that a new certificate of occupancy, continued certificate of
occupancy, site plan approval, smoke detector inspection or any other government
approval is required as a condition to the conveyance of the Property, Seller,
at its sole cost and expense, shall comply with such requirement and deliver to
Purchaser evidence of such compliance on the Closing Date.

                                   ARTICLE 10

                               CLOSING ADJUSTMENTS

      10.1 Adjustment Time. All apportionments and adjustments shall be made as
of 12:00 midnight on the Closing Date.

      10.2 Description of Items to be Adjusted. The following apportionments and
adjustments shall be made:

            (a) real estate taxes assessed against the Lands and Improvements
            based upon the calendar year assessed;

            (b) the amount of the real estate transfer taxes payable in
            connection with the conveyance of the Property shall be deducted
            from the Purchase Price and shall be paid by Purchaser directly to
            the taxing authority;

            (c) if there are any confirmed or unconfirmed special assessments
            against the Lands or the Improvements, Seller shall pay same if the
            work giving rise to the assessment was completed prior to the date
            of this Agreement, but if the work giving rise to the assessment was
            not completed prior to the date of this Agreement, same shall be
            paid or assumed by Purchaser;

            (d) rents and all other charges (including cost reimbursement
            payments) actually paid under the Leases, provided, however, that,
            if any rents shall be

<PAGE>

            accrued and unpaid at the Closing Date, the rents collected by
            Purchaser on or after the Closing Date shall first be applied to all
            rents due at the time of such collection on or after the Closing
            Date with the balance payable to Seller to the extent of rents
            delinquent as of the Closing Date; provided, further, that Purchaser
            shall not be required to institute any proceeding to collect any
            rents accrued and unpaid on the Closing Date. Any rent or additional
            rent paid to Seller after the Closing Date shall promptly be
            remitted to Purchaser. If Seller shall not have received all accrued
            and unpaid rents due it as of the Closing Date within one hundred
            twenty (120) days thereafter, Seller, at its sole cost and expense,
            shall be entitled to bring such actions or proceedings not affecting
            possession, the validity of the Leases or any security held by
            Purchaser thereunder as it shall desire to collect any such accrued
            and unpaid rents, and Purchaser shall, at no cost to Purchaser,
            cooperate with Seller in any such action;

            (e) payments under any Reciprocal Easement Agreement;

            (f) all other income and expense from the Property of every type and
            nature. If any of the foregoing cannot be apportioned at the Closing
            Date because of the unavailability of the amounts which are to be
            apportioned, such items shall be apportioned as soon as practicable
            after the Closing Date; and

            (g) sewer, water, gas, electric, telephone and other utility charges
            shall not be apportioned but shall be paid by Seller based upon
            current bills or meter readings.

      10.3 Security Deposits. At closing, Purchaser shall be entitled to a
credit against the Purchase Price for any security deposits (including any
interest thereon to which a tenant may be entitled) held by Seller pursuant to
the Leases or Seller shall turn over such security deposits and interest to
Purchaser.

      10.4 Closing Costs. Seller and Purchaser shall pay their own legal fees
related to this transaction. Purchaser shall pay all its costs associated with
its due diligence investigation of the Property, the cost of title searches and
survey, title insurance premiums and the cost of recording the deed. Seller

<PAGE>

shall pay the cost of curing any Title Objections, removing any Voluntary
Encumbrances and all transfer taxes.

                                   ARTICLE 11

                                DEFAULT; REMEDIES

      11.1 Default by Purchaser. Seller may terminate this Agreement by notice
to Purchaser at any time prior to the Closing Date in the event of (a) a default
by Purchaser under this Agreement (which remains uncured for ten (10) days after
notice to Purchaser specifying such default and demanding that same be cured or
(b) a material breach by Purchaser of any representation or warranty expressly
set forth in this Agreement (a "Purchaser Default").

      11.2 Default by Seller. Purchaser may terminate this Agreement by notice
to Seller at any time prior to the Closing Date in the event of (a) a default by
Seller under this Agreement (which remains uncured for ten (10) days after
notice to Seller specifying such default and demanding that same be cured,
unless such default cannot be cured by the payment of money and cannot with due
diligence be wholly cured within such ten (10) day period, in which case Seller
may request a longer period as shall be necessary to cure such default, so long
as Seller proceeds promptly to cure such default within such ten (10) day
period, prosecute such cure to completion with due diligence within sixty (60)
days and advise Purchaser of the actions which Seller is taking and the progress
being made) or (b) a material breach by Seller of any representation or warranty
expressly set forth in this Agreement that is not cured within the applicable
grace period (a "Seller Default").

      11.3 Remedies.

            (a) Of Seller. In the event of a Purchaser Default, Seller shall, as
            its sole and exclusive remedy hereunder, have the right to terminate
            this Agreement and receive the Deposit and such payment shall
            constitute and be liquidated and agreed damages, whereupon the
            parties hereto shall be relieved of any further liability or
            obligation to each other, it being expressly understood that the
            receipt by Seller of such monies shall be the sole and exclusive
            right and remedy of Seller and constitutes a fair and reasonable
            amount for the damage sustained by Seller

<PAGE>

            by reason of Purchaser's breach of this Agreement. Seller hereby
            waive and release any right to seek specific performance against
            Purchaser.

            (b) Of Purchaser. In the event of a Seller Default, Purchaser shall
            be entitled, either (i) to specific performance, or (ii) to
            terminate this Agreement and receive from Seller the Deposit or
            (iii) to waive the Seller Default and consummate the transactions
            contemplated hereby, provided that if Seller willfully causes a
            Seller Default or sells the Property or any portion thereof to a
            third party, or takes any action that renders the remedy of specific
            performance impossible or impracticable to obtain, Seller shall be
            liable for any damages sustained by Purchaser.

                                   ARTICLE 12

                                  MISCELLANEOUS

      12.1 Brokerage Commission and Finder's Fee. Seller and Purchaser agree
that they have dealt with each other and not through any real estate broker,
investment banker, person, firm or entity who would, by reason of such dealings,
be able to claim a real estate brokerage, business opportunity brokerage or
finder's fee as the procuring cause of this transaction, except the Broker.
Seller and Purchaser agree to indemnify the other and hold the other harmless of
and from any and all loss, cost, damage, injury or expense arising out of, or in
any way related to, assertions, by any other person, firm or entity of a claim
to real estate brokerage, business opportunity brokerage or finder's fee based
on alleged contacts between the claiming party and the indemnifying party which
have resulted in allegedly providing a broker or finder with the right to claim
such commission or finder's fee. Purchaser agrees to pay the Broker a commission
pursuant to a separate agreement if, as and when title closes and Seller shall
have no liability to the Broker. The provisions of this Section 12.1 shall
survive the closing of title.

      12.2 Assignment. Purchaser shall have the right to assign this Agreement
to an affiliate provided (a) a copy of the executed assignment is delivered to
Seller not less that five (5) days prior to the Closing Date, (b) the assignee
assumes all obligations of Purchaser hereunder, and (c) Purchaser remains
primarily liable hereunder as a principal and not as a guarantor or surety.
Purchaser shall also have the right to designate a

<PAGE>

nominee or nominees to take title to the Property, and in such event all of the
benefits of this Agreement pertaining to the Property shall inure to the benefit
of and be enforceable by such nominee.

      12.3 Notices. Any demand, notice or other communication required or
permitted to be given hereunder shall be in writing, and shall be delivered
personally, by telecopy (with a hard copy and a transmission confirmation sent
by a recognized overnight national courier service (such as Federal Express) for
next business day delivery) or by certified mail, return receipt requested,
first-class postage prepaid to the parties at the addresses set forth below (or
to such other addresses as the parties may specify by due notice to the other):

            To Seller:

                     c/o Berger & Bornstein, P.A.,
                     237 South Street
                     Morristown, New Jersey 07962
                     Attention: Lawrence S. Berger
                     Fax: 973-993-5854
                     Telephone: 973-993-8600

            To Purchaser:

                    Keystone Operating Partnership, L.P.
                    200 Four Falls Corporate Center, Suite 208
                    West Conshohocken, Pennsylvania 19428
                    Attention: John B. Begier, Executive Vice President,
                               Chief Investment Officer
                    Fax Number 484-530-0130
                    Telephone: 484-530-1845

            and

                    Keystone Operating Partnership, L.P.
                    200 Four Falls Corporate Center, Suite 208
                    West Conshohocken, Pennsylvania 19428
                    Attention: Saul A. Behar, Senior Vice President,
                               General Counsel and Secretary
                    Fax Number 484-530-0131
                    Telephone: 484-530-1825

            with copies to:

                     Drinker Biddle & Shanley LLP

<PAGE>

                     500 Campus Drive
                     Florham Park, New Jersey 07932-1047
                     Attention: Gerald W. Hull, Jr., Esq.
                     Fax: 973-360-9831
                     Telephone: 973-549-7000

            To Escrow Agent:

                     Chicago Title Insurance Company
                     56 Washington Street
                     Toms River, New Jersey 08754
                     Attention: Ralph A. Romano
                     Fax Number 631-727-2124
                     Telephone 631-727-2197

Any notice delivered to a party's designated address by (a) personal delivery,
(b) recognized overnight national courier service, or (c) certified mail, return
receipt requested, shall be deemed to have been received by such party at the
time the notice is delivered to such party. Any notice sent by fax to the
party's designated fax number shall be effective upon receipt, provided receipt
occurs before 5:00 PM on a business day in the State of New Jersey. Confirmation
by the courier delivering any notice given pursuant to this Section 12.3 shall
be conclusive evidence of receipt of such notice. Each party hereby agrees that
it will not refuse or reject delivery of any notice given hereunder, that it
will acknowledge, in writing, receipt of the same upon request by any other
party and that any notice rejected or refused by it shall be deemed for all
purposes of this Agreement to have been received by the rejecting party on the
date so refused or rejected, as conclusively established by the records of the
U.S. Postal Service or the courier service. Any notice given by an attorney for
a party shall be effective for all purposes.

      12.4 Successors and Assigns. The terms, covenants and conditions herein
contained shall be binding upon and inure to the benefit of the successors and
permitted assigns of the parties hereto.

      12.5 Recordation. This Agreement shall not be recorded. Nothing herein
shall be deemed to prevent Purchaser from filing Notices of Settlement.

      12.6 Governing Law. This Agreement shall be governed by, construed and
enforced in accordance with the laws of the State of New Jersey.

<PAGE>

      12.7 Incorporation of Prior Agreements. This Agreement contains the entire
understanding of the parties hereto with respect to the subject matter hereof,
and no prior or other written or oral agreement or undertaking pertaining to any
such matter shall be effective for any purpose.

      12.8 Modification of Agreement. This Agreement may not be amended or
modified, nor may any obligation hereunder be waived orally, and no such
amendment, modification or waiver shall be effective for any purpose unless it
is in writing and signed by the party against whom enforcement thereof is
sought.

      12.9 Further Assurances. After the Closing Date, Seller shall execute,
acknowledge and deliver, for no further consideration, all such assignments,
transfers, consents and other documents as Purchaser may reasonably request to
carry out the provisions of this Agreement.

      12.10 Invalidity. If any provision hereof shall be declared invalid by any
court or in any administrative proceedings, the provisions of this Agreement
shall be construed in such manner so as to preserve the validity hereof and the
substance of the transaction herein contemplated to the extent possible.

      12.11 Counterparts. This Agreement may be executed and delivered in
several counterparts, each of which, when so executed and delivered, shall
constitute an original, fully enforceable counterpart for all purposes.

      12.12 Tax Free Exchange. Seller agrees that it shall, upon written request
from Purchaser, reasonably cooperate in effecting a transaction commonly
referred to as a "like-kind exchange" or a "tax free exchange" in connection
with the transaction contemplated by this Agreement, provided that any such
exchange and the related documentation shall (a) be at the sole cost and expense
of Purchaser, (b) not require Seller to incur any obligations or liabilities,
contingent or otherwise, to third parties, (c) not delay the closing hereunder
(d) not include Seller taking title to the replacement property or otherwise
becoming involved in a transaction with a third party and (e) shall not make
Purchaser's obligations hereunder contingent upon its ability to effectuate such
exchange. Purchaser agrees to indemnify and hold Seller harmless from and
against any additional cost or expense in connection with such Seller's
participation in such exchange.

<PAGE>

      IN WITNESS WHEREOF, the parties have executed this Agreement as of the
date set forth above.

                             Seller:

                             KULLER ROAD REALTY HOLDINGS, L.L.C.
                             A New Jersey Limited Liability Company

                             By: United States Land Resources, L.P. a
                                 [                         ],

                             By: United States Realty Resources, Inc.,
                             General Partner

                                            By: /s/ Lawrence S. Berger
                                                --------------------------------
                                            Name:  Lawrence S. Berger
                                            Title: President


                             Purchaser:

                             KEYSTONE OPERATING PARTNERSHIP, LP

                             By: Keystone Operation Trust

                             By: /s/ Saul A. Behar
                                 ------------------------------------------
                                 Name:  Saul A. Behar
                                 Title: Senior Vice President and Secretary

                            JOINDER BY TITLE INSURER

      By execution hereof, the Title Insurer hereby agrees to hold the Deposit
in accordance with the provisions of this Agreement.

                                            CHICAGO TITLE INSURANCE
                                            COMPANY


                                            By: /s/ Ralph A. Romano
                                                --------------------------------
                                               Name:  Ralph A. Romano
                                               Title: R.V.P.