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                                                                    EXHIBIT 10.5

                              MKS INSTRUMENTS, INC.

                       NONSTATUTORY STOCK OPTION AGREEMENT
           GRANTED UNDER THE SECOND RESTATED 1995 STOCK INCENTIVE PLAN
           -----------------------------------------------------------


1) Grant of Option.
   ---------------

     This agreement evidences the grant by MKS Instruments, Inc., a
Massachusetts corporation (the "Company"), on [Stock Date] (the "Grant Date") to
[First Name] [Last Name] an employee of the Company (the "Participant"), of an
option to purchase, in whole or in part, on the terms provided herein and in the
Company's Second Restated 1995 Stock Incentive Plan (the "Plan"), a total of
[Stock] shares (the "Shares") of common stock, no par value per share, of the
Company ("Common Stock") at [Stock Price] per Share. Unless earlier
terminated, this option shall expire on [Expire] (the "Final Exercise Date").

     It is intended that the option evidenced by this agreement shall not be an
incentive stock option as defined in Section 422 of the Internal Revenue Code of
1986, as amended and any regulations promulgated thereunder (the "Code"). Except
as otherwise indicated by the context, the term "Participant," as used in this
option, shall be deemed to include any person who acquires the right to exercise
this option validly under its terms.

2) Vesting Schedule.
   ----------------

     This option will become exercisable ("vest") as to ____% of the original
number of Shares [on the first anniversary of] the Grant Date and as to an
additional ____% of the original number of Shares at the end of each successive
_______-month period following the first anniversary of the Grant Date until the
______ anniversary of the Grant Date. This option shall expire upon, and will
not be exercisable after, the Final Exercise Date.

     The right of exercise shall be cumulative so that to the extent the option
is not exercised in any period to the maximum extent permissible it shall
continue to be exercisable, in whole or in part, with respect to all shares for
which it is vested until the earlier of the Final Exercise Date or the
termination of this option under Section 3 hereof or the Plan.

3) Exercise of Option.
   ------------------

          a) Form of Exercise. Each election to exercise this option shall be in
     writing, signed by the Participant, and received by the Company at its
     principal office, accompanied by this agreement, and payment in full in the
     manner provided in the Plan. The Participant may purchase less than the
     number of shares covered hereby, provided that no partial exercise of this
     option may be for any fractional share.

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          b) Continuous Relationship with the Company Required. Except as
     otherwise provided in this Section 3, this option may not be exercised
     unless the Participant, at the time he or she exercises this option, is,
     and has been at all times since the Grant Date, an employee, officer or
     director of, or consultant or advisor to, the Company or any parent or
     subsidiary of the Company as defined in Section 424(e) or (f) of the Code
     (an "Eligible Participant").

          c) Termination of Relationship with the Company. If the Participant
     ceases to be an Eligible Participant for any reason, then, except as
     provided in paragraphs (d) and (e) below, the right to exercise this option
     shall terminate three months after such cessation (but in no event after
     the Final Exercise Date), provided that this option shall be exercisable
     only to the extent that the Participant was entitled to exercise this
     option on the date of such cessation. Not withstanding the foregoing, if
     the Participant, prior to the Final Exercise Date, violates any provision
     of any employment contract, confidentiality and nondisclosure agreement or
     other agreement between the Participant and the Company, the right to
     exercise this option shall terminate immediately upon such violation.

          d) Exercise Period Upon Death or Disability. If the Participant dies
     or becomes disabled (within the meaning of Section 22(e)(3) of the Code)
     prior to the Final Exercise Date while he or she is an Eligible Participant
     and the Company has not terminated such relationship for "cause" as
     specified in paragraph (e) below, this option shall be exercisable, within
     the period of one year following the date of death or disability of the
     Participant, by the Participant, provided that this option shall be
     exercisable only to the extent that this option was exercisable by the
     Participant on the date of his or her death or disability, and further
     provided that this option shall not be exercisable after the Final Exercise
     Date.

          e) Discharge for Cause. If the Participant, prior to the Final
     Exercise Date, is discharged by the Company for "cause" (as defined below),
     the right to exercise this option shall terminate immediately upon the
     effective date of such discharge. "Cause" shall mean willful misconduct by
     the Participant or willful failure by the Participant to perform his or her
     responsibilities to the Company (including, without limitation, breach by
     the Participant of any provision of any employment, consulting, advisory,
     nondisclosure, or other similar agreement between the Participant and the
     Company), as determined by the Company, which determination shall be
     conclusive. The Participant shall be considered to have been discharged for
     "Cause" if the Company determines, within 30 days after the Participant's
     resignation, that discharge for cause was warranted.

     4. Withholding.
        -----------

          No Shares will be issued pursuant to the exercise of this option
     unless and until the Participant pays to the Company, or makes provision
     satisfactory to the Company for payment of, any federal, state or local
     withholding taxes required by law to be withheld in respect of this option.

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5. Nontransferability of Option.
   ----------------------------

     This option may not be sold, assigned, transferred, pledged or otherwise
encumbered by the Participant, either voluntarily or by operation of law, except
by will or the laws of descent and distribution, and, during the lifetime of the
Participant, this option shall be exercisable only by the Participant.

6. Provisions of the Plan.
   ----------------------

     This option is subject to the provisions of the Plan, a copy of which is
furnished to the Participant with this option.

     IN WITNESS WHEREOF, the Company has caused this option to be executed under
its corporate seal by its duly authorized officer. This option shall take effect
as a sealed instrument.




                                              MKS Instruments, Inc.


Dated: [Stock Date]                           By:
      --------------                             -------------------------------





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                            PARTICIPANT'S ACCEPTANCE

     The undersigned hereby accepts the foregoing option and agrees to the terms
and conditions thereof. The undersigned also acknowledges receipt of a copy of
the MKS Instruments, Inc., Second Restated 1995 Stock Incentive Plan.



                                         PARTICIPANT:


                                         Signature:
                                                   -----------------------------

                                         Printed name: [First Name] [Last Name]

                                             Date:
                                                  ------------------------------

                                             Address:



                                             [Stock] Shares
                                             --------------




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