Document:

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                                                                    Exhibit 10.8

                              MKS INSTRUMENTS, INC.

                   INTERNATIONAL EMPLOYEE STOCK PURCHASE PLAN

                                 2001 AMENDMENT

     Whereas, the above titled plan (the "Plan") was adopted by the Board of
Directors (the "Board") of MKS Instruments, Inc. (the "Company") and

     Whereas, Section 17 of the Plan provides that the Board may at any time,
and from time to time, amend this Plan in any respect,

     Now therefore, the Plan is hereby amended, effective for the Plan Period
beginning June 1, 2001, as follows:

     Section 2(a) is amended by deleting the requirement that a person be
employed by the Subsidiary for "at least six (6) months prior to enrolling in
the Plan" and substituting a requirement that a person be employed for "at least
three (3) months prior to enrolling in the Plan."

     Now therefore, the Plan is hereby further amended, effective for the Plan
Period beginning June 1, 2001, as follows:

     The first paragraph of Section 9 is hereby deleted in its entirety and the
following paragraph is inserted in lieu thereof:

     "9. PURCHASE OF SHARES. On the Offering Commencement Date of each Plan
Period, the Company will grant to each eligible employee who is then a
participant in the Plan an option ("Option") to purchase on the last business
day of such Plan Period (the "Exercise Date"), at the Option Price hereinafter
provided for, the largest number of shares (fractional or whole) of Common Stock
of the Company as does not exceed the number of shares determined by multiplying
$2,083 by the number of full months in the Offering Period and dividing the
results by the closing price (as defined below) on the Offering Commencement
Date of such Plan Period."

                            Adopted by the Board of Directors on April 19, 2001.<PAGE>
                                                                   Exhibit 10.25

                              MKS INSTRUMENTS, INC.

                       CONSENT, WAIVER AND FIRST AMENDMENT

                                TO CREDIT AGREEMENT

     This Consent, Waiver and First Amendment (the"Amendment") dated as of
January 28, 2002 concerns the Credit Agreement dated as of July 31, 2001 (the
"Credit Agreement"), by and among MKS Instruments, Inc. (the "Borrower"), Fleet
National Bank ("Fleet") and JPMorgan Chase Bank (formerly known as The Chase
Manhattan Bank, "Chase"; hereinafter Fleet and Chase may be referred to
individually as a "Lender" or collectively as the "Lenders"), and Fleet in its
capacity as agent for the Lenders. Capitalized terms used herein but not
otherwise defined shall have the meanings assigned to them in the Credit
Agreement.

     WHEREAS, the Borrower has requested that the Lender waive compliance with
certain covenants in the Credit Agreement and consent to its acquisition of ENI
Technology, Inc. and certain related transactions, as well as amend another
covenant in the Credit Agreement as a result of the effect of such acquisition;
and

     WHEREAS, the Lender is willing to agree to the Borrower's requests;

     NOW, THEREFORE, the Lenders and the Borrower agree as follows:

     Section 1. CONSENT AND WAIVER. The Lenders hereby consent to the
transactions contemplated by the Agreement and Plan of Merger with respect to
the Acquisition of the ENI Business, dated October 30, 2001, between the
Borrower and Emerson Electric Co. (the "Acquisition Agreement") including
without limitation the acquisition of ENI Technology, Inc. ("ENI") and waives
compliance with Sections 8.1(b) and 8.4 of the Loan Agreement with respect to
such transactions.

     Section 2. AMENDMENT OF THE LOAN AGREEMENT.

          (a)  Any and all references in the Credit Agreement or the other Loan
Documents to "The Chase Manhattan Bank" are hereby amended to read "JPMorgan
Chase Bank".

          (b)  Section 8.9 of the Credit Agreement is hereby amended by
deleting "$292,000,000" therefrom and replacing it with "$260,000,000".

     Section 3. REPRESENTATIONS AND WARRANTIES. The Borrower hereby represents
and warrants as follows:

          (a) The execution and delivery of this Amendment and the performance
of this Amendment, the Credit Agreement as amended hereby and each of the other
Loan Documents, and the transactions contemplated hereby and thereby, have been
authorized by all necessary corporate actions of the Borrower. This Amendment,
the Credit Agreement as amended hereby and each of the other Loan Documents
constitute the legal, valid and binding obligations of the Borrower, enforceable
against the Borrower in accordance with their respective terms.

<PAGE>

          (b) The Borrower has all requisite corporate power and authority to
execute, deliver and perform its obligations under this Amendment, the Credit
Agreement as amended hereby and each of the other Loan Documents. Neither the
authorization, execution, delivery or performance by the Borrower of this
Amendment nor the performance of the Credit Agreement as amended hereby or any
other Loan Document nor the performance of the transactions contemplated hereby
or thereby violates or will violate any provision of the corporate charter or
by-laws of the Borrower, or does or will, with the passage of time or the giving
of notice or both, result in a breach of or a default under, or require any
consent under or result in the creation of any lien, charge or encumbrance upon
any property or assets of the Borrower pursuant to, any material instrument,
agreement or other document to which the Borrower is a party or by which the
Borrower or any of its properties may be bound or affected.

          (c) The execution and delivery by the Borrower of this Amendment and
the performance by the Borrower of the Credit Agreement as amended hereby and
the Loan Documents do not and will not violate any provision of law or
regulation applicable to the Borrower, or any writ, order or decree of any court
or governmental or regulatory authority or agency applicable to the Borrower.

          (d) The representations and warranties contained in Article V of the
Credit Agreement are true and correct, and the Borrower and its Subsidiaries are
in compliance with all covenants set forth in Article VIII of the Credit
Agreement, provided that for this purpose that all references to the "Disclosure
Schedule" in such Articles V and VIII shall be deemed to mean the Disclosure
Schedule attached hereto, which is true and complete.

     Section 4. LOAN DOCUMENTS. This Amendment shall be a Loan Document for all
purposes.

     Section 5. CONDITIONS TO EFFECTIVENESS. The effectiveness of this Amendment
is conditioned on the following:

          (a) The Borrower and the Lenders shall each have executed and
delivered a counterpart of this Amendment;

          (b) The representations and warranties contained in Article V of the
Credit Agreement shall be true and correct in all material respects as of the
date hereof as though made on and as of the date hereof;

          (c) No Default or Event of Default under the Loan Agreement shall have
occurred and be continuing;

          (d) The conditions set forth in Section 6.1 of the Credit Agreement
shall have been met as of the date hereof, provided that for purposes thereof
and Section 5.5 of the Credit Agreement, the "Balance Sheet Date" shall mean
September 30, 2001 and the financial statements referred to therein shall mean
the unaudited statements for the period ended September 30, 2001, that have been
furnished to the Lenders.

                                      -2-
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          (e) Promptly following the closing under the Acquisition Agreement,
the Borrower shall cause to be delivered to the Lenders a guaranty of the
Obligations by ENI in the form attached here to as well as a certificate of the
secretary of ENI as to the votes of ENI's directors authorizing the execution
and delivery of such guaranty and the incumbency of the officers authorized to
execute such guaranty on behalf of ENI.

          (f) The Lenders shall have received a certificate of the clerk of the
Borrower as to the votes of Borrower's directors authorizing the execution and
delivery of this Amendment and the incumbency of the officers authorized to
execute this Amendment on behalf of the Borrower.

     Section 6. MISCELLANEOUS.

          (a) On and after the date hereof, each reference in the Loan Agreement
to "this Agreement" or words of like import shall mean and be deemed to be a
reference to the Credit Agreement as amended hereby.

          (b) Except as amended and modified hereby, the Credit Agreement is in
all respects ratified and confirmed as of the date hereof, and the terms,
covenants and agreements therein shall remain in full force and effect.

          (c) This Amendment and the modifications to the Credit Agreement set
forth herein shall be deemed to be a document executed under seal and shall be
governed by and construed in accordance with the laws of The Commonwealth of
Massachusetts.

          (d) This Amendment may be executed in counterparts, each of which
shall be deemed an original, but all of which together shall constitute one and
the same document.

                  [Remainder of page intentionally left blank.]

                                      -3-
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     IN WITNESS WHEREOF, the parties have caused this Amendment to be duly
executed as of the date and the year first above written.

                                          MKS INSTRUMENTS, INC.

                                          By:  /s/ Ronald C. Weigner
                                             ------------------------------
                                          Title: Vice President and Chief
                                                 Financial Officer

                                          FLEET NATIONAL BANK

                                          By:  /s/ Daniel G. Head
                                             -------------------------------
                                          Title: Vice President

                                          JP MORGAN CHASE BANK

                                          By:  /s/ A. Neil Sweeny
                                             -------------------------------
                                          Title: Vice President

                                      -4-

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