Document:

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                                                                    Exhibit 10.1

                             MKS INSTRUMENTS, INC.

                 SECOND RESTATED 1995 STOCK INCENTIVE PLAN

1.    PURPOSE

The purpose of this Second Restated 1995 Stock Incentive Plan (the "Plan") of
MKS Instruments, Inc., a Massachusetts corporation (the "Company"), is to
advance the interests of the Company's stockholders by enhancing the Company's
ability to attract, retain and motivate persons who make (or are expected to
make) important contributions to the Company by providing such persons with
equity ownership opportunities and performance-based incentives and thereby
better aligning the interests of such persons with those of the Company's
stockholders. Except where the context otherwise requires, the term "Company"
shall include any present or future subsidiary corporations of MKS Instruments,
Inc. as defined in Section 424(f) of the Internal Revenue Code of 1986, as
amended, and any regulations promulgated thereunder (the "Code").

2.    ELIGIBILITY

All of the Company's employees, officers, directors, consultants and advisors
are eligible to be granted options, restricted stock, or other stock-based
awards (each, an "Award") under the Plan. Any person who has been granted an
Award under the Plan shall be deemed a "Participant."

3.    ADMINISTRATION, DELEGATION

      a.    ADMINISTRATION BY BOARD OF DIRECTORS. The Plan will be administered
by the Board of Directors of the Company (the "Board"). The Board shall have
authority to grant Awards and to adopt, amend and repeal such administrative
rules, guidelines and practices relating to the Plan as it shall deem advisable.
The Board may correct any defect, supply any omission or reconcile any
inconsistency in the Plan or any Award in the manner and to the extent it shall
deem expedient to carry the Plan into effect and it shall be the sole and final
judge of such expediency. All decisions by the Board shall be made in the
Board's sole discretion and shall be final and binding on all persons having or
claiming any interest in the Plan or in any Award. No director or person acting
pursuant to the authority delegated by the Board shall be liable for any action
or determination relating to or under the Plan made in good faith.

      b.    DELEGATION TO EXECUTIVE OFFICERS. To the extent permitted by
applicable law, the Board may delegate to one or more executive officers of the
Company, who are also members of the Board, if required by law, the power to
make Awards and exercise such other powers under the Plan as the Board may
determine, provided that the Board shall fix the maximum number of shares
subject to Awards and the maximum number of shares for any one Participant to be
made by such executive officers. The Chief Executive Officer of the Company may
grant Awards to non-executive officer employees of the Company in amounts not to
exceed 35,000 shares to any one employee.

      c.    APPOINTMENT OF COMMITTEES. To the extent permitted by applicable
law, the Board may delegate any or all of its powers under the Plan to one or
more committees or
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subcommittees of the Board (a "Committee"). If and when the common stock, no par
value per share, of the Company (the "Common Stock) is registered under the
Securities Exchange Act of 1934 (the "Exchange Act"), the Board shall appoint
one such Committee of not less than two members, each member of which shall be
an "outside director" within the meaning of Section 162(m) of the Code and a
"non-employee director" as defined in Rule 16b-3 promulgated under the Exchange
Act." All references in the Plan to the "Board" shall mean the Board or a
Committee of the Board or the executive officer referred to in Section 3(b) to
the extent that the Board's powers or authority under the Plan have been
delegated to such Committee or executive officer.

4.    STOCK AVAILABLE FOR AWARDS

      a.    NUMBER OF SHARES. Effective January 1, 2002 and subject to
adjustment under Section 4(c), the number of shares of Common Stock available
for Awards under the Plan: (i) shall annually increase by 5% of the total shares
of the Company's outstanding Common Stock on January 1 of each year; and (ii) in
the event of an increase in the total shares of the Company's Common Stock after
January 1 of any such year in connection with the acquisition of any
corporation, partnership or other business entity by the Company (whether by
merger, stock purchase or otherwise), shall increase by 5% of such increased
amount. Such increases shall occur until such time as the aggregate number of
shares of Common Stock which may be issued under the Plan is 15,000,000 shares,
subject to adjustment under Section 4(c)." If any Award expires or is
terminated, surrendered or canceled without having been fully exercised or is
forfeited in whole or in part or results in any Common Stock not being issued,
the unused Common Stock covered by such Award shall again be available for the
grant of Awards under the Plan, subject, however, in the case of Incentive Stock
Options (as hereinafter defined), to any limitation required under the Code.
Shares issued under the Plan may consist in whole or in part of authorized but
unissued shares or treasury shares. All share amounts set forth in this plan
reflect the 2,110-for-1 stock split approved by the Board of Directors of the
Company on December 31, 1997 (the "1997 Stock Split").

      b.    PER-PARTICIPANT LIMIT. Subject to adjustment under Section 4(c), for
Awards granted after the Common Stock is registered under the Exchange Act, the
maximum number of shares with respect to which Awards may be granted to any
Participant under the Plan shall be 900,000 per calendar year. The
per-participant limit described in this Section 4(b) shall be construed and
applied consistently with Section 162(m) of the Code.

      c.    ADJUSTMENT TO COMMON STOCK. In the event of any stock split, stock
dividend, recapitalization, reclassification, reorganization, merger,
consolidation, combination, exchange of shares, liquidation, spin-off or other
similar change in capitalization or event, or any distribution to holders of
Common Stock other than a normal cash dividend, (i) the number and class of
securities available under this Plan, (ii) the number and class of security and
exercise price per share subject to each outstanding Option, (iii) the
repurchase price per security subject to each outstanding Restricted Stock
Award, (iv) the per-Participant limit set forth in Section 4(b) and (v) the
terms of each other outstanding stock-based Award shall be appropriately
adjusted by the Company (or substituted Awards may be made, if applicable) to
the extent the Board shall determine, in good faith, that such an adjustment (or
substitution) is necessary and
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appropriate. If this Section 4(c) applies and Section 8(e)(1) also applies to
any event, Section 8(e)(1) shall be applicable to such event and this Section
4(c) shall not be applicable.

5.    STOCK OPTIONS

      a.    GENERAL. The Board may grant options to purchase Common Stock (each,
an "Option") and determine the number of shares of Common Stock to be covered by
each Option, the exercise price of each Option and the conditions and
limitations applicable to the exercise of each Option, including conditions
relating to applicable federal or state securities laws, as it considers
necessary or advisable. An Option which is not intended to be an Incentive Stock
Option (as hereinafter defined) shall be designated a "Nonstatutory Stock
Option."

      b.    INCENTIVE STOCK OPTIONS. An Option that the Board intends to be an
"incentive stock option" as defined in Section 422 of the Code (an "Incentive
Stock Option") shall only be granted to employees of the Company and shall be
subject to and shall be construed consistently with the requirements of Section
422 of the Code. The Company shall have no liability to a Participant, or any
other party, if an Option (or any part thereof) which is intended to be an
Incentive Stock Option is not an Incentive Stock Option.

      c.    EXERCISE PRICE.  The Board shall establish the exercise price
at the time each Option is granted and specify it in the applicable option
agreement.

      d.    DURATION OF OPTIONS.  Each Option shall be exercisable at such
times and subject to such terms and conditions as the Board may specify in
the applicable option agreement.  No Option will be granted for a term in
excess of 10 years.

      e.    EXERCISE OF OPTION.  Options may be exercised only by delivery
to the Company of a written notice of exercise signed by the proper person
together with payment in full as specified in Section 5(f) for the number
of shares for which the Option is exercised.

      f.    PAYMENT UPON EXERCISE.  Common Stock purchased upon the
exercise of an Option granted under the Plan shall be paid for as follows:

            i.    in cash or by check, payable to the order of the Company;

            ii.    except as the Board may otherwise provide in an Option
Agreement, delivery of an irrevocable and unconditional undertaking by a
creditworthy broker to deliver promptly to the Company sufficient funds to pay
the exercise price, delivery by the Participant to the Company of a copy of
irrevocable and unconditional instructions to a creditworthy broker to deliver
promptly to the Company cash or a check sufficient to pay the exercise price, or
by delivery of shares of Common Stock owned by the Participant valued at the
fair market value as determined by the Board in good faith ("Fair Market
Value"), which Common Stock was owned by the Participant at least six months
prior to such delivery;

            iii.    to the extent permitted by the Board and explicitly provided
in an Option Agreement (i) by delivery of a promissory note of the Participant
to the Company on terms determined by the Board, or (ii) by payment of such
other lawful consideration as the Board may determine; or
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            iv.    any combination of the above permitted forms of payment.

6.    RESTRICTED STOCK

      a.    GRANTS. The Board may grant Awards entitling recipients to acquire
shares of Common Stock, subject to the right of the Company to repurchase all or
part of such shares at their issue price or other stated or formula price (or to
require forfeiture of such shares if issued at no cost) from the recipient in
the event that conditions specified by the Board in the applicable Award are not
satisfied prior to the end of the applicable restriction period or periods
established by the Board for such Award (each, "Restricted Stock Award").

      b.    TERMS AND CONDITIONS. The Board shall determine the terms and
conditions of any such Restricted Stock Award, including the conditions for
repurchase (or forfeiture) and the issue price, if any. Any stock certificates
issued in respect of a Restricted Stock Award shall be registered in the name of
the Participant and, unless otherwise determined by the Board, deposited by the
Participant, together with a stock power endorsed in blank, with the Company (or
its designee). At the expiration of the applicable restriction periods, the
Company (or such designee) shall deliver the certificates no longer subject to
such restrictions to the Participant or if the Participant has died, to the
beneficiary designated, in a manner determined by the Board, by a Participant to
receive amounts due or exercise rights of the Participant in the event of the
Participant's death (the "Designated Beneficiary"). In the absence of an
effective designation by a Participant, Designated Beneficiary shall mean the
Participant's estate.

7.    OTHER STOCK-BASED AWARDS

The Board shall have the right to grant other Awards based upon the Common
Stock, having such terms and conditions as the Board may determine including the
grant of shares based upon certain conditions, the grant of securities
convertible into Common Stock and the grant of stock appreciation rights.

8.    GENERAL PROVISIONS APPLICABLE TO AWARDS

      a.    TRANSFERABILITY OF AWARDS. Except as the Board may otherwise
determine or provide in an Award, Awards shall not be sold, assigned,
transferred, pledged or otherwise encumbered by the person to whom they are
granted, either voluntarily or by operation of law, except by will or the laws
of descent and distribution, and, during the life of the Participant, shall be
exercisable only by the Participant. References to a Participant, to the extent
relevant in the context, shall include references to authorized transferees.

      b.    DOCUMENTATION.  Each Award under the Plan shall be evidenced
by a written instrument in such form as the Board shall determine.  Each
Award may contain terms and conditions in addition to those set forth in
the Plan.

      c.    BOARD DISCRETION.  Except as otherwise provided by the Plan,
each type of Award may be made alone or in addition or in relation to any
other type of Award.  The terms of each type of Award need not be
identical, and the Board need not treat Participants uniformly.

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      d.    TERMINATION OF STATUS. The Board shall determine the effect on an
Award of the disability, death, retirement, authorized leave of absence or other
change in the employment or other status of a Participant and the extent to
which, and the period during which, the Participant, the Participant's legal
representative, conservator, guardian or Designated Beneficiary may exercise
rights under the Award.

      e.    ACQUISITION EVENTS

            (1)   CONSEQUENCES OF ACQUISITION EVENTS. Upon the occurrence of an
Acquisition Event (as defined below), or the execution by the Company of any
agreement with respect to an Acquisition Event, the Board shall take any one or
more of the following actions with respect to then outstanding Awards: (i)
provide that outstanding Options shall be assumed, or equivalent Options shall
be substituted, by the acquiring or succeeding corporation (or an affiliate
thereof), provided that any such Options substituted for Incentive Stock Options
shall satisfy, in the determination of the Board, the requirements of Section
424(a) of the Code; (ii) if the acquisition or succeeding corporation refuses or
is unable to assume outstanding Options or grant Options in substitution
therefor pursuant to clause (i), upon written notice to the Participants,
provide that all then unexercised Options will become exercisable in full as of
a specified time (the "Acceleration Time") prior to the Acquisition Event and
will terminate immediately prior to the consummation of such Acquisition Event,
except to the extent exercised by the Participants between the Acceleration Time
and the consummation of such Acquisition Event; (iii) in the event of an
Acquisition Event under the terms of which holders of Common Stock will receive
upon consummation thereof a cash payment for each share of Common Stock
surrendered pursuant to such Acquisition Event (the "Acquisition Price"),
provide that all outstanding Options shall terminate upon consummation of such
Acquisition Event and each Participant shall receive, in exchange therefor, a
cash payment equal to the amount (if any) by which (A) the Acquisition Price
multiplied by the number of shares of Common Stock subject to such outstanding
Options (whether or not then exercisable), exceeds (B) the aggregate exercise
price of such Options; (iv) provide that all Restricted Stock Awards then
outstanding shall become free of all restrictions prior to the consummation of
the Acquisition Event; and (v) provide that any other stock-based Awards
outstanding (A) shall become exercisable, realizable or vested in full, or shall
be free of all conditions or restrictions, as applicable to each such Award,
prior to the consummation of the Acquisition Event, or (B), if applicable, shall
be assumed, or equivalent Awards shall be substituted, by the acquiring or
succeeding corporation (or an affiliate thereof).

            An "Acquisition Event" shall mean: (a) any merger or consolidation
which results in the voting securities of the Company outstanding immediately
prior thereto representing immediately thereafter (either by remaining
outstanding or by being converted into voting securities of the surviving or
acquiring entity) less than 50% of the combined voting power of the voting
securities of the Company or such surviving or acquiring entity outstanding
immediately after such merger or consolidation; (b) any sale of all or
substantially all of the assets of the Company; or (c) the complete liquidation
of the Company.

            (2)   ASSUMPTION OF OPTIONS UPON CERTAIN EVENTS. The Board may grant
Awards under the Plan in substitution for stock and stock-based awards held by
employees of another corporation who become employees of the Company as a result
of a
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merger or consolidation of the employing corporation with the Company or
the acquisition by the Company of property or stock of the employing
corporation. The substitute Awards shall be granted on such terms and conditions
as the Board considers appropriate in the circumstances.

      f.    WITHHOLDING. Each Participant shall pay to the Company, or make
provision satisfactory to the Board for payment of, any taxes required by law to
be withheld in connection with Awards to such Participant no later than the date
of the event creating the tax liability. The Board may allow Participants to
satisfy such tax obligations in whole or in part in shares of Common Stock,
including shares retained from the Award creating the tax obligation, valued at
their Fair Market Value; provided, however, that the total tax withholding where
stock is being used to satisfy such tax obligations cannot exceed the Company's
minimum statutory withholding obligations (based on minimum statutory
withholding rates for federal and state tax purposes, including payroll taxes,
that are applicable to such supplemental taxable income). The Company may, to
the extent permitted by law, deduct any such tax obligations from any payment of
any kind otherwise due to a Participant.

      g.    AMENDMENT OF AWARD. The Board may amend, modify or terminate any
outstanding Award, including but not limited to, substituting therefor another
Award of the same or a different type, changing the date of exercise or
realization, and converting an Incentive Stock Option to a Nonstatutory Stock
Option, provided that the Participant's consent to such action shall be required
unless the Board determines that the action, taking into account any related
action, would not materially and adversely affect the Participant.

      h.    CONDITIONS ON DELIVERY OF STOCK. The Company will not be obligated
to deliver any shares of Common Stock pursuant to the Plan or to remove
restrictions from shares previously delivered under the Plan until (i) all
conditions of the Award have been met or removed to the satisfaction of the
Company, (ii) in the opinion of the Company's counsel, all other legal matters
in connection with the issuance and delivery of such shares have been satisfied,
including any applicable securities laws and any applicable stock exchange or
stock market rules and regulations, and (iii) the Participant has executed and
delivered to the Company such representations or agreements as the Company may
consider appropriate to satisfy the requirements of any applicable laws, rules
or regulations.

      i.    ACCELERATION. The Board may at any time provide that any Options
shall become immediately exercisable in full or in part, that any Restricted
Stock Awards shall be free of all restrictions or that any other stock-based
Awards may become exercisable in full or in part or free of some or all
restrictions or conditions, or otherwise realizable in full or in part, as the
case may be.

9.    MISCELLANEOUS

      a.    NO RIGHT TO EMPLOYMENT OR OTHER STATUS. No person shall have any
claim or right to be granted an Award, and the grant of an Award shall not be
construed as giving a Participant the right to continued employment or any other
relationship with the Company. The Company expressly reserves the right at any
time to dismiss or otherwise terminate its relationship with a Participant free
from any liability or claim under the Plan, except as expressly provided in the
applicable Award.

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      b.    NO RIGHTS AS STOCKHOLDER. Subject to the provisions of the
applicable Award, no Participant or Designated Beneficiary shall have any rights
as a stockholder with respect to any shares of Common Stock to be distributed
with respect to an Award until becoming the record holder of such shares.

      c.    EFFECTIVE DATE AND TERM OF PLAN. The Plan shall become effective on
the date on which it is adopted by the Board, but no Award granted to a
Participant designated as subject to Section 162(m) by the Board shall become
exercisable, vested or realizable, as applicable to such Award, unless and until
the Plan has been approved by the Company's stockholders. No Awards shall be
granted under the Plan after the completion of ten years from the earlier of
(i) the date on which the Plan was adopted by the Board or (ii) the date the
Plan was approved by the Company's stockholders, but Awards previously granted
may extend beyond that date.

      d.    AMENDMENT OF PLAN. The Board may amend, suspend or terminate the
Plan or any portion thereof at any time, provided that no Award granted to a
Participant designated as subject to Section 162(m) by the Board after the date
of such amendment shall become exercisable, realizable or vested, as applicable
to such Award (to the extent that such amendment to the Plan was required to
grant such Award to a particular Participant), unless and until such amendment
shall have been approved by the Company's stockholders.

      e.    STOCKHOLDER APPROVAL.  For purposes of this Plan, stockholder
approval shall mean approval by a vote of the stockholders in accordance
with the requirements of Section 162(m) of the Code.

      f.    GOVERNING LAW.  The provisions of the Plan and all Awards made
hereunder shall be governed by and interpreted in accordance with the laws
of The Commonwealth of Massachusetts, without regard to any applicable
conflicts of law rules or provisions.

                                        Adopted by the Board of Directors on
                                        November 30, 1995

                                        Approved by the Stockholders on May
                                        17, 1996

                                        Amended and Restated by the Board of
                                        Directors on December 31, 1997

                                        Amended and Restated by the
                                        Stockholders on January 9, 1998

                                        Amended and Restated by the Board of
                                        Directors on August 1, 2002<PAGE>
                                                                    Exhibit 10.6

                              MKS INSTRUMENTS, INC.

                SECOND RESTATED 1999 EMPLOYEE STOCK PURCHASE PLAN

      The purpose of this Plan is to provide eligible employees of MKS
Instruments, Inc. (the "Company") and certain of its subsidiaries with
opportunities to purchase shares of the Company's Common Stock, no par value per
share (the "Common Stock"), commencing on June 1, 1999; provided, that at such
time the Company's Common Stock shall be listed for trading on the Nasdaq
National Market or a national securities exchange. Seven hundred thousand
(700,000) shares of Common Stock in the aggregate have been approved for this
purpose. This Plan is intended to qualify as an "employee stock purchase plan"
as defined in Section 423 of the Internal Revenue Code of 1986, as amended (the
"Code") and the regulations promulgated thereunder, and shall be interpreted
consistent therewith.

      1.    ADMINISTRATION. The Plan will be administered by the Company's Board
of Directors (the "Board") or by a Committee appointed by the Board (the
"Committee"). The Board or the Committee has authority to make rules and
regulations for the administration of the Plan and its interpretation and
decisions with regard thereto shall be final and conclusive.

      2.    ELIGIBILITY. All employees of the Company, including Directors who
are employees, and all employees of any subsidiary of the Company (as defined in
Section 424(f) of the Code) designated by the Board or the Committee from time
to time (a "Designated Subsidiary"), including employees of the Company or any
designated Subsidiary who are "highly compensated" within the meaning of Section
414(q) of the Code, are eligible to participate in any one or more of the
Offerings (as defined in Section 9) to purchase Common Stock under the Plan
provided that:

            (a)   they are customarily employed by the Company or a Designated
      Subsidiary for more than 20 hours a week and for more than five months in
      a calendar year; and

            (b)   they have been employed by the Company or a Designated
      Subsidiary for at least three (3) months prior to enrolling in the Plan;
      and

            (c)   they are employees of the Company or a Designated Subsidiary
      on the first day of the applicable Plan Period (as defined below).

      No employee may be granted an option hereunder if such employee,
immediately after the option is granted, owns 5% or more of the total combined
voting power or value of the stock of the Company or any subsidiary. For
purposes of the preceding sentence, the attribution rules of Section 424(d) of
the Code shall apply in determining the stock ownership of an employee, and all
stock which the employee has a contractual right to purchase shall be treated as
stock owned by the employee.
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      3.    OFFERINGS. The Company will make one or more offerings ("Offerings")
to employees to purchase stock under this Plan. Offerings will begin each June 1
and December 1, or the first business day thereafter (the "Offering Commencement
Dates"). Each Offering Commencement Date will begin a six (6) month period (a
"Plan Period") during which Payroll deductions will be made and held for the
purchase of Common Stock at the end of the Plan Period. The Board or the
Committee may, at its discretion, choose a different Plan Period of twelve (12)
months or less for subsequent Offerings.

      4.    PARTICIPATION. An employee eligible on the Offering Commencement
Date of any Offering may participate in such Offering by completing and
forwarding a payroll deduction authorization form to the employee's appropriate
payroll office at least 30 days prior to the applicable Offering Commencement
Date. The form will authorize a regular payroll deduction from the Compensation,
as defined below, received by the employee during the Plan Period. Unless an
employee files a new form or withdraws from the Plan, his deductions and
purchases will continue at the same rate for future Offerings under the Plan as
long as the Plan remains in effect. The term "Compensation" means the amount of
money reportable on the employee's Federal Income Tax Withholding Statement,
including overtime, shift premium, incentive or bonus awards and any other
variable sales compensation and excluding allowances and reimbursements for
expenses such as relocation allowances for travel expenses, income or gains on
the exercise of Company stock options or stock appreciation rights, and similar
items, whether or not shown on the employee's Federal Income Tax Withholding
Statement, but including, in the case of salespersons, sales commissions to the
extent determined by the Board or the Committee.

      5.    DEDUCTIONS. The Company will maintain payroll deduction accounts for
all participating employees. With respect to any Offering made under this Plan,
an employee may authorize a payroll deduction in any whole percent amount up to
a maximum of 10% (or such lower percentage as may be established by the Board or
the Committee) of the Compensation he or she receives during the Plan Period or
such shorter period during which deductions from payroll are made. The minimum
payroll deduction is such percentage of compensation as may be established from
time to time by the Board or the Committee.

      No employee may be granted an Option (as defined in Section 9) which
permits his rights to purchase Common Stock under this Plan and any other
employee stock purchase plan (as defined in Section 423(b) of the Code) of the
Company and its subsidiaries, to accrue at a rate which exceeds $25,000 of the
fair market value of such Common Stock (determined at the Offering Commencement
Date of the Plan Period) for each calendar year in which the Option is
outstanding at any time.

                                       2
<PAGE>
      6.    DEDUCTION CHANGES. An employee may decrease, subject to section 5
hereof or discontinue his payroll deduction once during any Plan Period, by
filing a new payroll deduction authorization form. However, an employee may not
elect to increase his payroll deduction during a Plan Period. If an employee
elects to discontinue his payroll deductions during a Plan Period, but does not
elect to withdraw his funds pursuant to Section 8 hereof, funds deducted prior
to his election to discontinue will be applied to the purchase of Common Stock
on the Exercise Date (as defined below).

      7.    INTEREST. Interest will not be paid on employee accounts.

      8.    WITHDRAWAL OF FUNDS. An employee may at any time prior to the close
of business on the last business day in a Plan Period and for any reason
permanently draw out the balance accumulated in the employee's account and
thereby withdraw from participation in an Offering. Partial withdrawals are not
permitted. The employee may not begin participation again during the remainder
of the Plan Period. The employee may participate in any subsequent Offering in
accordance with terms and conditions established by the Board or the Committee.

      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.

      The purchase price for each share purchased will be 85% of the closing
price of the Common Stock on (i) the first business day of such Plan Period or
(ii) the Exercise Date, whichever closing price shall be less. Such closing
price shall be (a) the closing price on any national securities exchange on
which the Common Stock is listed, (b) the closing price of the Common Stock on
the Nasdaq National Market or (c) the average of the closing bid and asked
prices in the over-the-counter-market, whichever is applicable, as published in
The Wall Street Journal. If no sales of Common Stock were made on such a day,
the price of the Common Stock for purposes of clauses (a) and (b) above shall be
the reported price for the next preceding day on which sales were made.

      Each employee who continues to be a participant in the Plan on the
Exercise Date shall be deemed to have exercised his Option at the Option Price
on such date and shall be deemed to have purchased from the Company the number
of full shares of Common Stock reserved for the

                                       3
<PAGE>
purpose of the Plan that his accumulated payroll deductions on such date will
pay for, but not in excess of the maximum number determined in the manner set
forth above.

      Any balance remaining in an employee's payroll deduction account at the
end of a Plan Period will be automatically refunded to the employee, except that
any balance which is less than the purchase price of one share of Common Stock
will be carried forward into the employee's payroll deduction account for the
following Offering, unless the employee elects not to participate in the
following Offering under the Plan, in which case the balance in the employee's
account shall be refunded.

      10.   ISSUANCE OF CERTIFICATES. Certificates representing shares of Common
Stock purchased under the Plan may be issued only in the name of the employee,
in the name of the employee and another person of legal age as joint tenants
with rights of survivorship, or (in the Company's sole discretion) in the name
of a brokerage firm, bank or other nominee holder designated by the employee.
The Company may, in its sole discretion and in compliance with applicable laws,
authorize the use of book entry registration of shares in lieu of issuing stock
certificates.

      11.   RIGHTS ON RETIREMENT, DEATH OR TERMINATION OF EMPLOYMENT. In the
event of a participating employee's termination of employment prior to the last
business day of a Plan Period, no payroll deduction shall be taken from any pay
due and owing to an employee and the balance in the employee's account shall be
paid to the employee or, in the event of the employee's death, (a) to a
beneficiary previously designated in a revocable notice signed by the employee
(with any spousal consent required under state law) or (b) in the absence such a
designated beneficiary, to the executor or administrator of the employee's
estate or (c) if no such executor or administrator has been appointed to the
knowledge of the Company, to such other person(s) as the Company may, in its
discretion, designate. If, prior to the last business day of the Plan Period,
the Designated Subsidiary by which an employee is employed shall cease to be a
subsidiary of the Company, or if the employee is transferred to a subsidiary of
the Company that is not a Designated Subsidiary, the employee shall be deemed to
have terminated employment for the purposes of this Plan.

      12.   OPTIONEES NOT STOCKHOLDERS. No employee shall have any rights as a
stockholder with respect to any shares of Common Stock to be distributed with
respect to an Option until becoming the record holder or such shares.
Notwithstanding the foregoing, in the event the Company effects a split of the
Common Stock by means of a stock dividend (and the exercise price of and the
number of shares subject to such Option are adjusted as of the date of the
distribution of the dividend rather than as of the record date for such
dividend), then an optionee who is deemed to have exercised an Option between
the record date and the distribution

                                       4
<PAGE>
date for such stock dividend shall be entitled to receive, on the distribution
date, the stock dividend with respect to the shares of Common Stock.

      13.   RIGHTS NOT TRANSFERABLE. Rights under this Plan are not transferable
by a participating employee other than by will or the laws of descent and
distribution, and are exercisable during the employee's lifetime only by the
employee.

      14.   APPLICATION OF FUNDS. All funds received or held by the Company
under this Plan may be combined with other corporate funds and may be used for
any corporate purpose.

      15.   ADJUSTMENT IN CASE OF CHANGES AFFECTING COMMON STOCK. In the event
of a subdivision of outstanding shares of Common Stock, or the payment of a
dividend in Common Stock, the number of shares approved for this Plan, and the
share limitation set forth in Section 9, shall be increased proportionately, and
such other adjustment shall be made as may be deemed equitable by the Board or
the Committee. In the event of any other change affecting the Common Stock, such
adjustment shall be made as may be deemed equitable by the Board or the
Committee to give proper effect to such event.

      16.   MERGER. If the Company shall at any time merge or consolidate with
another corporation and the holders of the capital stock of the Company
immediately prior to such merger or consolidation continue to hold at least 80%
by voting power of the capital stock of the surviving corporation ("Continuity
of Control"), the holder of each Option then outstanding will thereafter be
entitled to receive at the next Exercise Date upon the exercise of such Option
for each share as to which such Option shall be exercised the securities or
property which a holder of one share of the Common Stock was entitled to upon
and at the time of such merger or consolidation, and the Board or the Committee
shall take such steps in connection with such merger or consolidation as the
Board or the Committee shall deem necessary to assure that the provisions of
Section 15 shall thereafter be applicable, as nearly as reasonably may be, in
relation to the said securities or property as to which such holder of such
Option might thereafter be entitled to receive thereunder.

      In the event of a merger or consolidation of the Company with or into
another corporation which does not involve Continuity of Control, or of a sale
of all or substantially all of the assets of the Company while unexercised
Options remain outstanding under the Plan, all outstanding Options shall be
cancelled by the Board or the Committee as of the effective date of any such
transaction, provided that notice of such cancellation shall be given to each
holder of an Option, and each holder of an Option shall have the right to
exercise such Option in full based on payroll deductions then credited to his
account as of a date determined by the Board or the Committee, which date shall
not be less than ten (10) days preceding the effective date of such transaction.

                                       5
<PAGE>
      17.   AMENDMENT OF THE PLAN. The Board may at any time, and from time to
time, amend this Plan in any respect, except that (a) if the approval of any
such amendment by the shareholders of the Company is required by Section 423 of
the Code, such amendment shall not be effected without such approval, and (b) in
no event may any amendment be made which would cause the Plan to fail to comply
with Section 423 of the Code.

      18.   SUFFICIENT SHARES. In the event that the total number of shares of
Common Stock specified in elections to be purchased under any Offering plus the
number of shares purchased under previous Offerings under this Plan exceeds the
maximum number of shares issuable under this Plan, the Board or the Committee
will allot the shares then available on a pro rata basis.

      19.   TERMINATION OF THE PLAN. This Plan may be terminated at any time by
the Board. Upon termination of this Plan all amounts in the accounts of
participating employees shall be promptly refunded.

      20.   GOVERNMENTAL REGULATIONS. The Company's obligation to sell and
deliver Common Stock under this Plan is subject to listing on a national stock
exchange or quotation on the Nasdaq National Market and the approval of all
governmental authorities required in connection with the authorization, issuance
or sale of such stock.

      21.   GOVERNING LAW. The Plan shall be governed by Massachusetts law
except to the extent that such law is preempted by federal law.

                                       6
<PAGE>
      22.   ISSUANCE OF SHARES. Shares may be issued upon exercise of an Option
from authorized but unissued Common Stock, from shares held in the treasury of
the Company, or from any other proper source.

      23.   NOTIFICATION UPON SALE OF SHARES. Each employee agrees, by entering
the Plan, to promptly give the Company notice of any disposition of shares
purchased under the Plan where such disposition occurs within two years after
the date of grant of the Option pursuant to which such shares were purchased or
one year after the date of exercise of the Option.

      24. WITHHOLDING. Each employee shall, no later than the date of the event
creating the tax liability, make provision satisfactory to the Board for payment
of any taxes required by law to be withheld in connection with any transaction
related to Options granted to or shares acquired by such employee pursuant to
the Plan. The Company may, to the extent permitted by law, deduct any such taxes
from any payment of any kind otherwise due to an employee.

      25.   EFFECTIVE DATE. The effective date of the plan is June 1, 1999.

            Adopted by the Board of Directors on February 10, 1999

            Approved by the Stockholders on February 17, 1999

            Amended and Restated by the Board of Directors on April 22, 1999

            Amended and Restated by the Board of Directors on August 1, 2002

                                       7

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