DUFFY HARTWELL LIMITED PARTNERSHIP

                                COMMERCIAL LEASE

1.   PARTIES:

DUFFY HARTWELL LIMITED PARTNERSHIP,  a Massachusetts limited partnership located
at 411 Waverley Oaks Rd. Waltham MA.,  LESSOR,  which  expression  shall include
its,  successors,  and assigns where the context so admits, does hereby lease to
SPECTRUM  MEDICAL  TECHNOLOGIES,  INC.  a  Delaware  corporation  located at 4-B
Strathmore  Rd. Natick MA.  LESSEE,  which  expression  shall include its heirs,
successors, executors,  administrators, and assigns where the context so admits,
and the LESSEE hereby leases the following described Premises:

2.   PREMISES:

Twenty-five  Thousand (25,000) sq. ft., more or less, (the "Leased Premises") in
the  LESSOR'S  Building  located at 45 Hartwell  Ave.  Lexington  MA,  including
exclusive  use of the loading  platform all as shown on Exhibit A, "Floor Plan",
attached hereto,  together with the right to use in common, with others entitled
thereto,  any  hallways,  and  stairways  necessary  for  access to said  Leased
Premises.

Appurtenant  to the  Premises  the LESSEE  shall have the right,  in common with
others  entitled  thereto,  to  access  ways,  walkways  and  any  other  common
facilities necessary for access to or beneficial use of the Leased Premises.

LESSEE shall have right to use  Eighty-eight  unassigned  parking  spaces in the
parking areas adjacent to the Buildings on the site. LESSEE shall have rights in
common  with  other  lessees to use of the common  entrance  serving  the Leased
Premises.

3.   TERM:

The  term  of  this  lease  shall  be  for  Five  (5)  years  commencing  on the
Commencement Date (defined below) and ending on May 31, 2000.

The  Commencement  Date shall be the later of completion  of the Lessor's  work,
Exhibit B, or June 1, 1995.  The  Lessor's  work shall be deemed  complete  upon
issuance of a certificate of occupancy for the Premises by the Town of Lexington
MA.

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4.   RENT:

         The LESSEE shall pay to LESSOR rent at the rates per year, shown below,
which rent shall be payable in advance in the monthly  installments  shown below
on the first day of each month.

         YEARS            ANNUAL RENT        MO. RENT          $/SF RATE

         1 - 5             $412,500         $34,375.00           $16.50


5.   SECURITY DEPOSIT:

Upon the execution of this lease,  the LESSEE shall pay to the LESSOR the amount
of $34,375,  which shall be held as a security for the LESSEE'S  performance  as
herein  provided  and  promptly  refunded to the LESSEE at the end of this lease
subject to the LESSEE'S satisfactory compliance with the conditions hereof.

6.   RENT ADJUSTMENT:

     A. TAX ADJUSTMENT

If in any tax year  commencing with the fiscal year 1997 (the fiscal year ending
June 30, 1997),  the real estate taxes on the land and  buildings,  of which the
Leased Premises are a part, are in excess of the amount of the real estate taxes
thereon for the fiscal year 1996  (hereinafter  called the "Base Year"),  LESSEE
will pay to LESSOR as  additional  rent  hereunder,  when and as  designated  by
notice in writing by LESSOR,  Fifty (50%)  percent of such excess that may occur
in each year of the term of this lease or any  extension or renewal  thereof and
proportionately  for  any  part of a  fiscal  year.  LESSOR'S  demand  shall  be
accompanied  by a copy of the  applicable  tax  bill or  bills  and a  statement
showing the manner of calculation of LESSEE'S proportionate share of such taxes.
If the  LESSOR  obtains an  abatement  of any such  excess  real  estate  tax, a
proportionate  share of such  abatement,  less  the  reasonable  fees and  costs
incurred in obtaining the same, if any, shall be refunded to the LESSEE.  LESSEE
may itself, or with any co-tenant,  seek review of the assessed valuation of the
property of witch the Leased Premises are a part, or otherwise seek abatement of
real estate  taxes in any year in which the LESSOR  declines to seek such review
or reduction, provided it shall do so at its own cost or expense.

For purposes of this adjustment the fiscal year 1996 tax rate shall be $1.08 per
square foot, or $54,472.08 for the land and building of which the lease premises
are a part.

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     B. OPERATING COSTS:

The LESSEE  shall pay to the LESSOR as  additional  rent  hereunder  when and as
designated by notice in writing by LESSOR, Fifty (50%) per cent of any operating
costs incurred  during the calendar year which are in excess of $4.00 per square
foot.  LESSOR'S  demand shall be  accompanied  by a statement of the  applicable
operating  costs and a statement  showing the manner of  calculation of LESSEE'S
proportionate  share of such costs.  In the event LESSEE wishes  verification of
the costs and its share,  LESSOR  will  authorize  its'  independent  C.P.A.  to
provide  certification  of the statement  and charges to the LESSEE,  and LESSEE
shall bear the expense of the C.P.A. certification. The operating costs increase
shall be prorated  should this lease be in effect with respect to only a portion
of any calendar year, or which pertain to less than a fully  occupied  building.
Operating costs are defined for the purpose of this agreement as:

         Water and Sewer Charges for the Premises
         Heating, Ventilation and Air Conditioning
         Maintenance Expenses of Lessor
         Cleaning Expenses
         Management Expenses (allocated at Five (5%) percent of rent)
         Insurance

Exceptions to Operating Expenses are defined in Exhibit E.

     C. BUILDING ACCESS AND OPERATING EXPENSES

The LESSEE  shall have  unlimited  access to the  Building.  However,  Operating
Expenses are calculated  based upon daily  operating hours of 7:00 AM to 6:00 PM
five days a week.  In the event LESSEE usage  outside those hours may be subject
to additional operating expenses.

7.   UTILITIES:

The LESSEE  shall pay, as they become due, all bills for  electricity  and other
utilities (whether they are used for furnishing heat or other purposes) that are
furnished to the Leased  Premises and which are separately  metered.  The LESSOR
agrees to provide  utility  services  to the  leased  premises,  all  subject to
interruption  due to any  accident,  to the making of repairs,  alterations,  or
improvements,  to labor difficulties, to trouble in obtaining fuel, electricity,
service,  or supplies from the sources from which they are usually  obtained for
said building, or to any cause beyond the LESSOR'S control.

LESSOR shall have no obligation to provide utilities or equipment other than the
utilities and equipment within the premises as of the Commencement  Date of this
lease  which  include the HVAC now  serving  the Leased  Premises.  In the event
LESSEE  requires  additional  utilities  or  equipment,   the  installation  and
maintenance  thereof shall be the LESSEE'S sole  obligation, 

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provided that such  installation  shall be the subject to the written consent of
the LESSOR.  Costs for the installation of separate metering for utilities shall
be borne by the LESSOR.

8.   USE OF LEASED PREMISES:

The LESSEE shall use the Leased  Premises only for the purpose of office,  light
manufacturing and R&D purposes.

9.   COMPLIANCE WITH LAW:

The LESSEE  acknowledges  that no trade or occupation  shall be conducted in the
Leased Premises or use made thereof which will be unlawful,  improper,  noisy or
offensive,  or contrary to any law or any municipal by-law or ordinance in force
in the Town of Lexington in which the premises are situated.

10.  FIRE INSURANCE:

The  LESSEE  shall not permit  any use of the  Leased  Premises  which will make
voidable any insurance on the property of which the Leased  Premises are a part,
or on the  contents  of said  property  or which shall be contrary to any law or
regulation  from time to time  established  by the New  England  Fire  Insurance
Rating  Association,  or any similar body  succeeding to its powers.  The LESSEE
shall on demand reimburse the LESSOR,  and all other tenants all extra insurance
premiums caused by the LESSEE'S use of the premises.

11.  MAINTENANCE:

     A. LESSEE'S OBLIGATIONS

The LESSEE agrees to maintain the Leased Premises in as good condition as at the
beginning of the term,  fair wear and tear and damage by fire and other casualty
only excepted,  and whenever  necessary,  to replace plate glass and other glass
therein, and upon occupancy the LESSEE acknowledges that the Leased Premises are
then in good order and the glass  whole.  The LESSEE shall not permit the Leased
Premises to be overloaded,  damaged, stripped, or defaced, nor suffer any waste.
LESSEE shall obtain  written  consent of LESSOR before  erecting any sign on the
exterior  of the  Leased  Premises,  which  consent  shall  not be  unreasonably
withheld or delayed.

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     B. LESSOR'S OBLIGATIONS

The LESSOR  agrees to maintain the structure of the building of which the Leased
Premises are a part, the HVAC,  mechanical,  electrical and plumbing facilities,
fire protection,  parking lot, exterior lighting, exterior window frames and the
common areas of the building in the same condition as it is at the  commencement
of the term or as it may be put in  during  the term of this  lease,  reasonable
wear and tear,  damage by fire and other  casualty  only  excepted,  unless such
maintenance  is  required  because of the LESSEE or those for whose  conduct the
LESSEE is legally  responsible.  LESSOR  shall  maintain  access ways and common
areas of the land in neat and orderly condition  including clearance of snow and
ice in the walk ways and parking lot.  LESSOR shall keep the building and common
areas under its control in  compliance  with all current and future  zoning laws
and other applicable municipal laws, regulations and ordinances.

12.  ALTERATIONS/ADDITIONS:

The LESSEE  shall not make  structural  alterations  or  additions to the Leased
Premises,  but may make non-structural  alterations provided the LESSOR consents
thereto in writing, which consent shall not be unreasonably withheld or delayed.
All such  allowed  alterations  shall be at  LESSEE'S  expense  and  shall be in
quality at least equal to the present construction.  LESSEE shall not permit any
mechanics' liens, or similar liens, to remain upon the Leased Premises for labor
and material  furnished to LESSEE or claimed to have been furnished to LESSEE in
connection  with  work of any  character  performed  or  claimed  to  have  been
performed  at the  direction  of  LESSEE  and  shall  cause  any such lien to be
released  of  record  forthwith  without  cost to  LESSOR.  Any  alterations  or
improvements  made by the LESSEE  shall become the property of the LESSOR at the
termination  of  occupancy as provided  herein.  Notwithstanding  the  foregoing
sentence, LESSEE may, at its sole option, submit its plans for any alteration or
improvement to LESSOR in writing before  installation with a request for removal
at LESSEE'S  expense upon  termination of this lease,  and LESSOR'S  approval of
such request,  which may require  restoration  of damages caused by the removal,
shall not be unreasonably withheld or delayed.

13.  ASSIGNMENT SUBLEASING:

The  LESSEE  shall  not  assign or  sublet  the whole or any part of the  Leased
Premises  without LESSOR'S prior written consent which shall not be unreasonably
withheld or delayed. Notwithstanding such consent, LESSEE shall remain liable to
LESSOR for the payment of all rent and for the full performance of the covenants
and conditions of this lease.

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14.  SUBORDINATION:

This lease shall be subject and  subordinate to any and all mortgages,  deeds of
trust  and  other  instruments  in the  nature  of a  mortgage,  now or any time
hereafter,  which may  constitute  a lien or liens on the  property of which the
Leased  Premises  are a part and the  LESSEE  shall,  when  requested,  promptly
execute and deliver such written  instruments  as shall be necessary to show the
subordination  of this lease to said  mortgages,  deeds,  of trust or other such
instruments in the nature of a mortgage,  provided, however, that the LESSEE may
thereupon  request  and  receive  the  mortgagee's  reciprocal   non-disturbance
agreement.

15.  LESSOR'S ACCESS:

The LESSOR or agents of the LESSOR may, at reasonable times and upon appropriate
notice,  (normally one day's prior notice) enter to view the Leased Premises and
may remove  placards  and signs not  approved and affixed to the exterior of the
Leased Premises as herein  provided,  and make repairs and alterations as LESSOR
should  elect to do. The LESSOR may show the Leased  Premises to others,  and at
any time within six (6) months before the  expiration of the term,  may affix to
any  suitable  part of the lease  premises a notice for  letting or selling  the
Leased Premises or property of which the Leased Premises are a part and keep the
same so affixed without  hindrance or molestation.  LESSOR shall use best effort
to minimize  inconvenience  and interference  with LESSEE and LESSEE'S  business
operations.

16.  INDEMNIFICATION & LIABILITY:

The LESSEE shall save the LESSOR harmless from all loss and damage occasioned by
the use or escape  of water or by the  bursting  of  pipes,  as well as from any
claim or damage  resulting  from neglect in not  removing  snow and ice from the
roof of the  building  or from the  sidewalks  bordering  upon the  premises  so
leased, or by any nuisance made or suffered on the Leased Premises,  unless such
loss is caused by the  neglect of the  LESSOR.  The removal of snow and ice from
the   sidewalks   bordering   upon  the  Leased   Premises   shall  be  LESSOR'S
responsibility.  LESSOR  shall  save the  LESSEE  harmless  from  loss or damage
occasioned by acts or omissions of the LESSOR, its employees or agents.

17.  LESSEE'S LIABILITY INSURANCE:

The LESSEE shall  maintain with respect to the Leased  Premises and the property
of which the Leased Premises are a part comprehensive public liability insurance
in the amount of $1 million Combined Single Limit with property damage insurance
in the same limit in responsible  companies qualified to do to persons or damage
to property as provided.  The LESSEE shall deposit with the LESSOR  certificates
for such insurance at or prior to the  commencement  of the term, and thereafter
within  (30)  days  prior  to the  expiration  of any  such  policies.  All such
insurance  certificates  shall provide that such policies  shall not be canceled
without  at least ten (10) days  prior  written  notice  to each  assured  named
therein.

18.  FIRE, CASUALTY AND EMINENT DOMAIN:

Should a substantial  portion of the Leased  Premises,  or the property of which
they are a part, be substantially damaged by fire or other casualty, or be taken
by eminent domain, the LESSOR may elect to terminate this lease. When such fire,
casualty,  or taking renders the Leased  

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Premises   substantially   unsuitable   for  their  intended  use,  a  just  and
proportionate  abatement  of rent shall be made,  and the  LESSEE,  may elect to
terminate this lease if:

     (a) the LESSOR  fails to give  written  notice  within  thirty (30) days of
     intention to restore Leased Premises, or

     (b) the  LESSOR  fails  to  restore  the  Leased  Premises  to a  condition
     substantially  suitable for their  intended use within  ninety (90) days of
     said fire, casualty or taking.

The LESSOR reserves,  and the LESSEE grants to the LESSOR,  all rights which the
LESSEE may have for damages or injury to the Leased  Premises  for any taking by
eminent  domain,  except  for  damage to the  LESSEE'S  fixtures,  property,  or
equipment.

19.  DEFAULT & BANKRUPTCY:

In the event that:

     (a) The LESSEE shall default in the payment of any  installment  of rent or
     other sum herein  specified  and such default  shall  continue for ten (10)
     days after written notice thereof; or

     (b) The LESSEE shall default in the  observance of performance of any other
     of the LESSEE'S covenants,  agreements,  or obligations  hereunder and such
     default shall not be corrected within thirty (30) days after written notice
     thereof   (except  if  such  default  is  not  cured  due  to  governmental
     restrictions or other causes beyond the control of LESSEE, then such thirty
     (30) day period shall be extended for a reasonable additional period); or

     (c) The LESSEE shall be declared  bankrupt or  insolvent  according to law,
     or, if any assignment shall be made of LESSEE'S property for the benefit of
     creditors,  then the  LESSOR  shall have the right  thereafter,  while such
     default continues,  to re-enter and take complete  possession of the Leased
     Premises,  to declare the term of this lease ended, and remove the LESSEE'S
     effects,  without  prejudice to any remedies  which might be otherwise used
     for  arrears  of rent or other  default.  The LESSOR  shall use  reasonable
     efforts  to relet the  Premises.  The  LESSEE  shall  indemnify  the LESSOR
     against all loss of rent and other  payments  which the LESSOR may incur by
     reason of such  termination  during the residue of the term.  If the LESSEE
     shall  default,  after  reasonable  notice  thereof,  in the  observance or
     performance  of any conditions or covenants on LESSEE'S part to be observed
     or performed  under or by virtue of any of the provisions in any article of
     this lease,  the LESSOR  without  being under any  obligation  to do so and
     without  thereby  waiving  such  default,  may remedy such  default for the
     account  and at the  expense  of  the  LESSEE.  If  the  LESSOR  makes  any
     expenditures  or  incurs  any  obligations  for the  payment  of  money  in
     connection therewith,  including but not limited to, reasonable attorneys's
     fees in  instituting,  prosecuting  or defending any action or  proceeding,
     such sums paid or  obligations  incurred,  with interest at the rate of 12%
     percent  per annum and costs,  shall be 

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     paid to the LESSOR by the LESSEE as additional rent.

20.  NOTICE:

Any notice from the LESSOR to the LESSEE  relating to the Leased  Premises or to
the  occupancy  thereof,  shall be deemed  duly  served,  if left at the  Leased
Premises  addressed  to  the  LESSEE,  or if  mailed  to  the  Leased  Premises,
registered  or  certified  mail,  return  receipt  requested,  postage  prepaid,
addressed  to the LESSEE.  Any notice from the LESSEE to the LESSOR  relating to
the Leased Premises or to the occupancy thereof, shall be deemed duly served, if
mailed to the LESSOR by registered or certified mail, return receipt  requested,
postage prepaid,  addresses to the LESSOR at such address as the LESSOR may from
time to time advise in writing. Until such advice all rent shall be paid and all
notices sent to the LESSOR at 411 Waverley Oaks Road, Waltham MA 02154.

21.  SURRENDER:

The LESSEE shall at the expiration or other termination of this lease remove all
LESSEE'S goods and effects from the Leased Premises,  (including, without hereby
limiting the  generality of the  foregoing  all signs and  lettering  affixed or
painted by the LESSEE,  either  inside or outside the Leased  Premises).  LESSEE
shall deliver to the LESSOR the Leased Premises and all keys, locks thereto, and
other fixtures connected  therewith and all alterations and additions made to or
upon the Leased  Premises,  in good condition,  fair wear and tear and damage by
fire or other  casualty only excepted.  In the event of the LESSEE'S  failure to
remove any of LESSEE'S property from the premises,  LESSOR is hereby authorized,
without liability to LESSEE for loss or damage thereto,  and at the sole risk of
LESSEE,  to remove and store any of the  property  at  LESSEE'S  expense,  or to
retain same under LESSOR'S control or to sell at public or private sale, without
notice,  any or all of the property not so removed and to apply the net proceeds
of such sale to the payment of any sum hereunder, or to destroy such property.

22.  BROKERAGE:

The Brokers named herein:  Cushman & Wakefield and Leggat McCall Grubb and Ellis
warrant  that  they  are  duly   licensed  as  such  by  the   Commonwealth   of
Massachusetts,  and join in this agreement and become parties hereto, insofar as
any provisions of this agreement  expressly apply to them, and to any amendments
or modifications of such provisions to which they agree in writing.

LESSOR agrees to pay the above named Brokers upon the term  commencement  date a
fee for 

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<PAGE>

professional  services as agreed  between  LESSOR and  Brokers  under a separate
agreement.

Each party  represents  and warrants  that it has not retained or dealt with any
other broker or brokers in connection with this Lease,  and each party agrees to
indemnify,  defend and save harmless the other party from any claims for fees or
commissions  arising  out of its  dealings  with a broker  with  respect to this
Lease.

23.  LATE FEES:

LESSEE  agrees that  because  actual  damages for a late payment or a dishonored
check are difficult to fix or ascertain,  but recognizing that damage and injury
result  therefore,  LESSEE agrees that if payments of rent and other obligations
are not  received  in hand by LESSOR  five (5) days  after the due date,  LESSEE
agrees to pay liquidated damages of $100.00 plus 18% per annum on the delinquent
amount from the due date.  The  postmark on the  payment  received  plus two (2)
days,  shall be  conclusive  evidence  of whether  the  payment  is  delinquent.
However,  LESSOR is not responsible for late deliveries by U.S. Mail.  Provided,
however,  that on a first occasion of such late payment,  LESSOR shall give five
days written notice to LESSEE prior to  application  of the  liquidated  damages
charge for late payment.  LESSEE agrees to pay a liquidated damage of $25.00 for
each dishonored  check. In the event that two or more of the LESSEE'S checks are
dishonored in a 12 month period, the LESSOR, in addition to other Rights,  shall
have the right to demand payment by Certified Check or Money Order.

24.  OTHER PROVISIONS:

It is also understood and agreed that:

     (a) The  attached  Addendum and Exhibits A., B., C., D., and E. are part of
     this Agreement.

     (b)  LESSEE  shall  have a Five  Year  option  to  renew  at  market  rates
     prevailing at the time of exercise of such option(s).  Such an option shall
     be exercised by written notice to LESSOR six months prior to the expiration
     of the then current term. See Addendum Part D for procedure.

     (c) LESSOR  shall  perform  the work  outlined  in  Exhibit  B,  "Build Out
     Specifications", at LESSOR'S expense, prior to the Commencement Date.

     (d) LESSEE shall have a Right of First Refusal on  additional  space in the
     building, in accordance with provisions of Exhibit D.

IN WITNESS WHEREOF, the said parties hereunto set their hand and seal as of this
day of March, 1996.

SPECTRUM MEDICAL TECHNOLOGIES, INC.         DUFFY HARTWELL LIMITED PARTNERSHIP
LESSEE                                      LESSOR

_________________________                   _____________________________
                                            NORMAN J. DUFFY,
                                            General Partner



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                       DUFFY HARTWELL LIMITED PARTNERSHIP

                            COMMERCIAL LEASE ADDENDUM

A. LESSEE OBLIGATIONS

1. Lessee shall not change the color or  appearance of the outside of the Leased
Premises except upon the prior written consent of the Lessor.

2. Lessee shall not post signs on or about the Premises except that Lessee shall
be entitled to sign space where  provided by Lessor in common with other lessees
in the Building.

3. The  parking  areas  shall not be used for  storage  of  unused,  damaged  or
unregistered vehicles, nor shall the Lessee store merchandise or other materials
in the parking areas.

4. Lessee shall not otherwise store vehicles,  containers, or refuse outside the
Leased  Premises,  except for routine parking of vehicles and delivery or pickup
of products or materials.

5. Lessee  shall be  responsible  to dispose of Lessee  trash and refuse  which
emanates from its manufacturing or R&D operations.

6. The Lessee may  maintain  insurance  required  by this Lease  under a blanket
policy of insurance which insures the Lessee and any affiliates of the Lessee.

7. No  animals,  reptiles  or pets of any kind  shall  be kept in or  about  the
building.

B. LESSOR OBLIGATIONS

1. Lessor  shall,  at its own cost and expense,  maintain in good  condition and
repair all structural components of the building containing the Leased Premises,
including the foundation,  floor,  walls and roof, common areas of the Building,
landscaping, parking areas and access ways.

2. Lessor shall remove snow and ice from the access roadway,  the parking areas,
and the walkways  which serve the  building,  and Lessor will remove snow or ice
from the roof of the building if, as and when the conditions  cause roof leakage
or threaten ice falls over access ways.

3. Lessor shall maintain with insurance  companies,  licensed in  Massachusetts,
all risk fire insurance  policies with extended  coverage  insuring the property
containing the Leased Premises 

<PAGE>

against loss or damage caused by fire or casualty in an amount equal to the full
replacement cost of the Building.

4. Lessor shall clean the Leased  Premises and common areas in conformance  with
Exhibit C. attached hereto.

C. SUBLEASING PROVISION

In the event Lessee requests consent of Lessor for sublease or assignment of all
or a material  portion of the Lease Premises,  Lessor may refuse consent for the
purpose  of  re-lease  of the  Leased  Premises  or the  portion  thereof to the
assignee,  the sub-lessee or to a third party.  Upon the mutual agreement of the
parties, hereto, this lease shall then terminate at a mutually agreed date as to
the Leased Premises or the portion  thereof,  as if the Lease had expired on its
termination date.

The Lessor shall be deemed to approve any  assignment  or sub-lease to a parent,
subsidiary or affiliate of the Lessee upon written  assurance by Lessee that the
subsequent use will be in conformance with and subject to section 8, above, "USE
OF LEASED PREMISES".

D. MARKET RATE RENT FOR RENEWAL OPTIONS

Upon receipt of written notice from the Lessee of intent to renew,  Lessor shall
respond  within thirty days with a quote for market rate rent.  The Lessee shall
respond within thirty (30) days agreeing to the quotation, rejecting the renewal
or requesting third party  determination of market rate. In the later event each
party shall then appoint a realty broker who is familiar with similar commercial
property in the Lexington  area,  they shall confer,  and each shall recommend a
market rate by writing to the parties.  In the event their  recommendations  are
joint or equal, this shall be market rate. If the  recommendations  differ by 5%
or less,  their  average  shall be deemed  market rate. In the event their rates
differ by a greater  amount they shall jointly  nominate a third such broker who
shall make an independent  recommendation of market rate. The two closest of the
three  recommendations shall then be averaged to establish the market rate. Each
party  hereto shall pay the expense of it nominee  broker,  and each shall share
equally the expense of a third, if required.  However,  in no event shall market
rate be less than the rate then payable by the Lessee.


<PAGE>



                                   EXHIBIT B.

                             BUILDOUT SPECIFICATIONS

The Lessor shall deliver the layout and location of offices,  rooms,  corridors,
lighting,  bathrooms,  plumbing,  electrical  services,  floors,  dock  area and
climate controls as presently located, in good operating  condition.  The Lessor
shall repaint wall  surfaces,  replace carpet and damaged tile flooring up to an
allowance of $15.00 per square yard,  replace  damaged or stained  ceiling tile,
and shall install new light bulbs where applicable, all to building standard, at
Lessor's sole cost.

The Lessor shall  provide the building and  facilities  in  compliance  with ADA
requirements for accessibility.

The Lessor shall remove cafeteria venting presently in place.

The Lessor shall also provide  kitchen  cabinets,  counter,  sink and dishwasher
equipment for the area marked cafeteria,  to Lessee  specification,  at Lessee's
cost. Such costs shall be payable to Lessor upon Occupancy.

The Lessor  shall take all  necessary  steps to correct the  condition  that has
caused the odor of oil in the Leased Premises.


<PAGE>



                                    EXHIBIT C

                                CLEANING SCHEDULE

NIGHTLY  Between the hours of 5:00 p.m.  and 6:00 a.m.  Monday  through  Friday,
Legal Holidays excepted

1.   Clean Lavatories as follows:

     (a)  Sweep and wash floors, using a disinfectant in wash water.

     (b)  Wash and polish all mirrors,  powder shelves,  bright work, and enamel
          surfaces.

     (c)  Thoroughly scour, wash and disinfect all basins, bowls and urinals.

     (d)  Wash and disinfect all toilet seats, both sides.

     (e)  Wash all partitions,  tile walls,  towel,  paper,  and sanitary napkin
          dispensers, and receptacles, as required.

     (f)  Empty and clean paper towel and sanitary disposal receptacles.

     (g)  Fill toilet tissue  holders,  soap  dispensers  and towel  dispensers,
          materials to be furnished by LESSOR.

2.   Empty and clear all waste receptacles, ash trays and sand urns.

3.   Wash, clean and disinfect water fountains and water coolers.

4.   Remove  rubbish and trash from LESSEE'S  premises  resulting  from business
     office use, but this shall not include  manufacturing or product  packaging
     materials, the removal of which is LESSEE'S responsibility.

5.   Vacuum LESSEE'S carpeted areas as needed.

6.   Damp mop floors in entrance foyers,  elevator lobbies, and public corridors
     if applicable.

7.   Wet sponge wipe table tops in LESSEE'S employee lounge,  including cleaning
     of any spills, if applicable.

8.   Keep sidewalks, and parking area clean and rubbish free.
<PAGE>

WEEKLY

1.   Damp mop all uncarpeted areas.

2.   Keep lawn and landscaping properly maintained, if applicable.

SEMI ANNUALLY

1.   Clean all ceiling and wall air supply and exhaust diffusers or grills.

ANNUALLY

1.   Wash all windows inside and out.

NOTE:

Manufacturing and Lab areas, and storage sections to be omitted.

HOLIDAYS

During the 10 legal holidays of the year no cleaning will be performed.


<PAGE>



                                   EXHIBIT D.

                   RIGHT OF FIRST REFUSAL ON ADDITIONAL SPACE

Lessee  shall have a right of first  refusal  on  additional  lease  space as it
becomes  available  during the term of this Lease  Agreement or any extension of
such term. This right is subject to any preexisting rights of other lessees. The
Lessor will use its best efforts to accommodate Lessee's space requirements.

The procedure for effecting the Right of First Refusal shall be exercised in the
following manner:

          (i)  Lessee  shall  in any  quarter  year  of the  lease  term  or its
               extension give to Lessor  written  notice of its projected  space
               requirements  and its  interest in space that is available or may
               become available for lease.

          (ii) Lessor,  within ten days of Lessee's  notice,  shall give written
               response   describing  to  Lessee  the  availability  of  or  the
               projected availability of floor space.  "Availability" shall mean
               and include any vacant space and any space which is or may become
               free of leasehold commitment. Such Lessor notice will contain the
               rental rate for which such space will be offered.

          (iii)If  the  Lessor  can  provide  such  space  by  relocation  of an
               existing  lessee,  Lessor shall, at the earliest  reasonable date
               consistent with discussion with the existing  lessee,  respond to
               the Lessee's  notice as set forth in the first  paragraph of this
               Section.

          (iv) Lessee  shall have  fourteen  (14) days to exercise  its right by
               written notice to Lessor to accept or reject  Lessor's notice and
               proposal.

          (v)  In the event Lessee,  by writing,  accepts such additional  space
               the parties will  forthwith,  within 30 days of Lessee's  written
               response,  execute a lease  agreement  or lease  modification  to
               reflect the additional  space, its rental rate, the adjusted term
               of Lease,  if any,  and such other  changes as may be required to
               reflect the additional space.

          (vi) In the event Lessee does not accept the Lessor's  proposal within
               the 14 day  period,  or in the event the  parties  are  unable to
               conclude a lease agreement for the additional premises within the
               above  thirty  day  period,  the  Lessee  shall be deemed to have
               refused the space and Lessor may offer and  contract for lease of
               the  space to third  parties,  the  Lessee's  rights  under  this
               provision having lapsed as to the proposed premises.


<PAGE>





                                    EXHIBIT E

                       EXCLUSIONS FROM OPERATING EXPENSES

The following  items shall be excluded in computing  LESSEE's share of operating
expenses applicable to the Leased Premises:

     1. Any ground lease rental;

     2. Costs of capital repairs or capital replacements (except as specifically
permitted  herein),  capital  improvements  and  equipment;  except  those:  (a)
required  by laws  enacted  on or after the date the  temporary  certificate  of
occupancy  issued for the LESSEE  work shall be validly  issued with the cost of
any such  improvements  and  equipment  depreciated  over the usual  life of the
improvement and/or equipment,  or (b) installed at the Leased Premises to reduce
operating  expenses,  with  the  cost of any  such  improvements  and  equipment
depreciated  at an annual  rate  reasonably  calculated  to equal the  amount of
operating  expenses to be saved in each  calendar year  throughout  the term (as
determined at the time LESSOR elected to proceed with the capital improvement or
acquisition of the capital equipment to reduce operating expenses);

     3. Rentals for items (except when needed in connection  with normal repairs
and  maintenance of the building  which shall be permitted)  which if purchased,
rather than rented, would constitute a capital improvement specifically excluded
in Subsection 2, above;

     4. Costs incurred by LESSOR for the repair for replacement of damage to the
building or its contents caused by fire or other casualty;

     5. Depreciation,  amortization,  lender's fees and interest payments except
as permitted pursuant to Subsection 2, above, and, if permitted, then determined
in  accordance  with  generally  accepted  accounting  principles,  consistently
applied  (as  applied  to  commercial   real  estate)  in  accordance  with  the
anticipated useful life of such item (as reasonably determined by LESSOR);

     6.  Overhead and profit  increments  paid to LESSOR or to  subsidiaries  or
affiliates of LESSOR for goods and/or services in the building to the extent the
same exceeds the cost of such goods  and/or  services  rendered by  unaffiliated
third parties on a competitive basis;

     7. Advertising and promotional expenditures, and the costs of acquiring and
installing signs in or on the building identifying the owner of the building;

     8. Interest,  principal,  points and fees on debts or  amortization  on any
mortgage or mortgages or any other debt instrument encumbering the building;
<PAGE>

     9. Any costs  associated  with gift taxes,  excise  taxes,  profit taxes or
capital levies;

     10. Costs incurred in connection with upgrading the building to comply with
handicap,  hazardous material,  fire and safety codes which were in effect prior
to the date of the lease or which become effective after lease commencement;

     11. Tax penalties incurred as a result of LESSOR's negligence, inability or
unwillingness to make payments when due, not attributable to LESSEE's failure to
make payments to LESSOR for such items in accordance with the lease;

     12. Any and all costs  arising from the presence of hazardous  materials or
substances (as defined by applicable Federal,  Massachusetts and local laws) now
or hereafter pertaining to the building ("Hazardous Substances") in or about the
building  including,  without  limitation,  Hazardous  Substances in the ground,
water, or soil;

     13. Costs to repair defects in the  construction of improvements  described
in Exhibit B. or defects in the building structure.

     14.  LESSOR's  general  corporate  overhead and general and  administrative
expenses  except as contained and allowed in the 5% Management Fee per provision
in Clause 6.B., above.

     15.  Costs of any items for which LESSOR is  reimbursed  by  insurance,  or
otherwise compensated by parties other than LESSEE's of the building;

     16. Any legal fees associated with the sale or refinancing of the building;

     17.  Costs for any  separate  utility  meters  LESSOR  may  install  in the
building,   unless  the  installation  is  required  by  a  utility  company  or
governmental entity.

     18.  Costs for  construction  in  compliance,  or  penalties  assessed  for
non-compliance  with the Americans  with  Disabilities  Act of 1990 (42.  U.S.C.
1281-1283).