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                                                                   Exhibit 10.10


                              MKS INSTRUMENTS, INC.

                         Restricted Stock Unit Agreement
  Initial Grant to Non-Employee Directors Under the 2004 Stock Incentive Plan

     AGREEMENT made this __ day of ________ 20__ (the "Grant Date"), between MKS
Instruments, Inc., a Massachusetts corporation (the "Company"), and (FIRST_NAME)
(LAST_NAME) (the "Participant").

     For valuable consideration, receipt of which is acknowledged, the parties
hereto agree as follows:

     1. General.

     The Company has granted to the Participant restricted stock units ("RSUs")
with respect to the number of shares set forth in Exhibit A hereto (the
"Shares") of common stock, no par value, of the Company ("Common Stock"),
subject to the terms and conditions set forth in this Agreement and in the
Company's 2004 Stock Incentive Plan (the "Plan"). The RSUs represent a promise
by the Company to deliver Shares upon vesting.

     2. Vesting Period.

     Subject to the terms and conditions of this Agreement (including the
Forfeiture provisions described in Section 3 below), the RSUs shall vest in
twelve (12) equal quarterly installments following the Grant Date. The date upon
which each quarterly installment vests shall be considered a "Vesting Date" for
the portion of the RSUs vesting on that date. As soon as practicable after the
Vesting Date, but in any event, within the period ending on the later to occur
of the date that is 2 1/2 months from the end of (i) the Participant's tax year
that includes the Vesting Date, or (ii) the Company's tax year that includes the
Vesting Date, the Company shall instruct its transfer agent to deposit the
Shares subject to the RSUs into the Participant's existing stock option account
(the "Account") at Fidelity Stock Plan Services, LLC, or such other broker with
which the Company has established a relationship ("Broker"), subject to payment
of all applicable withholding taxes.

     3. Forfeiture.

          (a) Definitions. For purposes of this Agreement, "Forfeiture" shall
mean any forfeiture of RSUs pursuant to Section 3(b) below. For purposes of this
Agreement, "service" with the Company shall include service as an employee,
officer or director of, or consultant or advisor to, the Company or any parent
or subsidiary of the Company as defined in Sections 424(e) or (f) of the
Internal Revenue Code.

          (b) Cessation of Service. In the event that the Participant ceases to
provide services to the Company for any reason or no reason, with or without
cause, prior to the final Vesting Date, all of the Participant's RSUs that have
not vested as of the date of such cessation shall automatically be forfeited as
of such cessation. In the event that the Participant ceases to provide services
to the Company by reason of death or disability prior to the Vesting Date, then
100% of the Participant's RSUs shall become immediately and fully vested and
shall no longer

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be subject to the Forfeiture provisions under this Agreement. For the purpose of
this Section 3, "disability" shall mean disability as defined in Section
216(i)(1) of the U.S. Social Security Act.

          (c) Change in Control. Notwithstanding the foregoing, upon the
effectiveness of a Change in Control, (as defined below), 100% of the
Participant's RSUs shall become immediately and fully vested and shall no longer
be subject to the Forfeiture provisions under this Agreement. For purposes of
this section "Change in Control" means the first to occur of any of the
following events: (I) any "person" (as that term is used in Section 13 and
14(d)(2) of the Securities Exchange Act of 1934 ("Exchange Act")) becomes the
beneficial owner (as that term is used in Section 13(d) of the Exchange Act),
directly or indirectly, of fifty percent (50%) or more of the Company's capital
stock entitled to vote in the election of directors; (II) the shareholders of
the Company approve any consolidation or merger of the Company, other than a
consolidation or merger of the Company in which the holders of the common stock
of the Company immediately prior to the consolidation or merger hold more than
fifty percent (50%) of the common stock of the surviving corporation immediately
after the consolidation or merger; or (III) the shareholders of the Company
approve the sale or transfer of all or substantially all of the assets of the
Company to parties that are not within a "controlled group of corporations" (as
defined in Code Section 1563) in which the Company is a member.

     4. Restrictions on Transfer.

     The Participant shall not sell, assign, transfer, pledge, hypothecate or
otherwise dispose of, by operation of law or otherwise (collectively "transfer")
any RSUs, or any interest therein, except that the Participant may transfer such
RSUs (i) to or for the benefit of any spouse, children, parents, uncles, aunts,
siblings, grandchildren and any other relatives approved by the Board of
Directors (collectively, "Approved Relatives") or to a trust established solely
for the benefit of the Participant and/or Approved Relatives, provided that such
RSUs shall remain subject to this Agreement (including without limitation the
terms of Forfeiture and the restrictions on transfer set forth in this Section
4) and such permitted transferee shall, as a condition to such transfer, deliver
to the Company a written instrument confirming that such transferee shall be
bound by all of the terms and conditions of this Agreement.

     5. Provisions of the Plan.

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

     6. No Compensation Deferral. Neither the Plan nor this Agreement is
intended to provide for an elective deferral of compensation that would be
subject to Section 409A ("Section 409A") of the U.S. Internal Revenue Code of
1986, as amended. The Company reserves the right, to the extent the Company
deems necessary or advisable in its sole discretion, to unilaterally amend or
modify the Plan and/or this Agreement to ensure that no awards (including
without limitation, the RSUs) become subject to the requirements of Section
409A.

     7. Withholding Taxes.


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          (a) The Company's obligation to deliver Shares to the Participant upon
the vesting of the RSUs shall be subject to the satisfaction of all income tax
(including federal, state and local taxes), social insurance, payroll tax,
payment on account or other tax related withholding requirements ("Withholding
Taxes").

          (b) The Participant has reviewed with the Participant's own tax
advisors the federal, state, local and foreign tax consequences of this grant
and the transactions contemplated by this Agreement. The Participant is relying
solely on such advisors and not on any statements or representations of the
Company or any of its agents. The Participant understands that the Participant
(and not the Company) shall be responsible for the Participant's own tax
liability that may arise as a result of this grant or the transactions
contemplated by this Agreement.

     8. Nature of the Grant. In signing this Agreement, the Participant
acknowledges that:

     (a) the Plan is established voluntarily by the Company, it is discretionary
     in nature and may be modified, amended, suspended or terminated by the
     Company at any time, unless otherwise provided in the Plan and this
     Agreement;

     (b) the grant of RSUs is voluntary and occasional and does not create any
     contractual or other right to receive future awards of RSUs, or benefits in
     lieu of RSUs even if RSUs have been awarded repeatedly in the past;

     (c) all decisions with respect to future grants of RSUs, if any, will be at
     the sole discretion of the Company;

     (d) the Participant's participation in the Plan is voluntary;

     (e) RSUs are an extraordinary item that do not constitute compensation of
     any kind for services of any kind rendered to the Company;

     (f) RSUs are not part of normal or expected compensation or salary for any
     purpose, including, but not limited to, calculation of any severance,
     resignation, termination, redundancy, end of service payments, bonuses,
     long-service awards, pension or retirement benefits or similar payments and
     in no event should be considered as compensation for, or relating in any
     way to, past services for the Company;

     (g) the future value of the underlying Shares is unknown and cannot be
     predicted with certainty;

     (h) if the Participant receives Shares upon vesting, the value of such
     Shares acquired on vesting of RSUs may increase or decrease in value;

     (i) in consideration of the grant of RSUs, no claim or entitlement to
     compensation or damages arises from termination of the RSUs or diminution
     in value of the RSUs or Shares received upon vesting of RSUs resulting from
     termination of the Participant's


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     service relationship by the Company (for any reason whatsoever and whether
     or not in breach of local labor laws) and the Participant irrevocably
     releases the Company from any such claim that may arise; if,
     notwithstanding the foregoing, any such claim is found by a court of
     competent jurisdiction to have arisen, then, by signing this Agreement, the
     Participant shall be deemed irrevocably to have waived his or her
     entitlement to pursue such claim; and

     (j) further, if the Participant ceases to provide services, the
     Participant's right to receive RSUs and vest under the Plan, if any, will
     terminate effective as of the date that the Participant is no longer
     actively providing services to the Company and will not be extended by any
     notice period mandated under local law; the Committee shall have the
     exclusive discretion to determine when the Participant is no longer
     actively providing services to the company for purposes of the Plan.

     9. Data Privacy Notice and Consent. The Participant hereby explicitly and
unambiguously consents to the collection, use and transfer, in electronic or
other form, of his or her personal data as described in this paragraph, by and
among, as applicable, and the Company and its subsidiaries and affiliates for,
among other purposes, implementing, administering and managing the Participant's
participation in the Plan. The Participant understands that the Company and its
subsidiaries hold certain personal information about the Participant, including
the Participant's name, home address, date of birth, social security number or
identification number, salary, job title, any Shares or directorships held in
the Company, details of all options or any other entitlement to Shares awarded,
canceled, exercised, vested, unvested or outstanding in the Participant's favor,
for the purpose of managing and administering the Plan ("Data"). The Participant
further understands that the Company and/or its subsidiaries will transfer Data
amongst themselves as necessary for various purposes, including implementation,
administration and management of the Participant's participation in the Plan,
and that the Company and/or any of its subsidiaries may each further transfer
Data to Broker or such other stock plan service provider or other third parties
assisting the Company with processing of Data. The Participant understands that
these recipients may be located in the United States, and that the recipient's
country may have different data privacy laws and protections than in the
Participant's country. The Participant authorizes them to receive, possess, use,
retain and transfer the Data, in electronic or other form, for the purposes
described in this section, including any requisite transfer to Broker or such
other stock plan service provider or other third party as may be required for
the administration of the Plan and/or the subsequent holding of Shares of stock
on the Participant's behalf. The Participant understands that he or she may, at
any time, request access to the Data, request any necessary amendments to it or
refuse or withdraw the consents herein, in any case without cost, by contacting
in writing. The Participant understands, however, that withdrawal of consent may
affect the Participant's ability to participate in or realize benefits from the
Plan. For more information on the consequences of refusal to consent or
withdrawal of consent, the Participant understands that he or she may contact
the Company.

     10. Miscellaneous.

          (a) No Rights to Service Relationship. The Participant acknowledges
and agrees that the vesting of the RSUs pursuant to Section 2 hereof is earned
only in accordance


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with the terms of such section. The Participant further acknowledges and agrees
that the transactions contemplated hereunder and the vesting schedule set forth
herein do not constitute an express or implied promise of a continued service
relationship as an employee, officer, director, consultant or advisor to the
Company or any subsidiary of the Company for the vesting period, for any period,
or at all.

          (b) Severability. The invalidity or unenforceability of any provision
of this Agreement shall not affect the validity or enforceability of any other
provision of this Agreement, and each other provision of this Agreement shall be
severable and enforceable to the extent permitted by law.

          (c) Waiver. Any provision for the benefit of the Company contained in
this Agreement may be waived, either generally or in any particular instance, by
the Board of Directors of the Company.

          (d) Binding Effect. This Agreement shall be binding upon and inure to
the benefit of the Company and the Participant and their respective heirs,
executors, administrators, legal representatives, successors and assigns,
subject to the restrictions on transfer set forth in Section 4 of this
Agreement.

          (e) Notice. All notices required or permitted hereunder shall be in
writing and deemed effectively given upon personal delivery or five days after
deposit in the United States Post Office, by registered or certified mail,
postage prepaid, addressed to the other party hereto at the address shown
beneath his or its respective signature to this Agreement, or at such other
address or addresses as either party shall designate to the other in accordance
with this Section 10(e).

          (f) Pronouns. Whenever the context may require, any pronouns used in
this Agreement shall include the corresponding masculine, feminine or neuter
forms, and the singular form of nouns and pronouns shall include the plural, and
vice versa.

          (g) Language. If the Participant has received this Agreement or any
other document related to the Plan translated into a language other than English
and if the translated version is different than the English version, the English
version will control.

          (h) Electronic Delivery. The Company may, in its sole discretion,
decide to deliver any documents related to participation in the Plan, RSUs
granted under the Plan or future RSUs that may be granted under the Plan by
electronic means or to request the Participant's consent to participate in the
Plan by electronic means. The Participant hereby consents to receive such
documents by electronic delivery and, if requested, to agree to participate in
the Plan through an on-line or electronic system established and maintained by
the Company or another third party designated by the Company.

          (i) Entire Agreement. This Agreement and the Plan constitute the
entire agreement between the parties, and supersedes all prior agreements and
understandings, relating to the subject matter of this Agreement.


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          (j) Amendment. This Agreement may be amended or modified only by a
written instrument executed by both the Company and the Participant.

          (k) Governing Law. This Agreement shall be construed, interpreted and
enforced in accordance with the internal laws of the Commonwealth of
Massachusetts without regard to any applicable conflicts of laws.

          (l) The Participant's Acknowledgments. The Participant acknowledges
that he or she: (i) has read this Agreement; (ii) has been represented in the
preparation, negotiation, and execution of this Agreement by legal counsel of
the Participant's own choice or has voluntarily declined to seek such counsel;
and (iii) understands the terms and consequences of this Agreement; and (iv) is
fully aware of the legal and binding effect of this Agreement.


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     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the day and year first above written.

                                        MKS INSTRUMENTS, INC.


                                        By:
                                            ------------------------------------
                                        Title: Chief Executive Officer &
                                               President
                                               90 Industrial Way
                                               Wilmington, MA 01887

                                        (First_Name) (Last_Name)


                                        Participants Signature:
                                                                ----------------
                                        Address: (Street), (BoxApt)
                                                 (City), (State) (Zip_Code)
                                                 (Country)


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                                                                       Exhibit A

                              [Stock Award Letter]


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