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                                                                     EXHIBIT 4.3

                                     AMENDED
                                       AND
                                    RESTATED
                                     BYLAWS
                                       OF
                               INPUT/OUTPUT, INC.
                        AS AMENDED THRU FEBRUARY 5, 2002

                                    ARTICLE I
                                     Offices

         Section 1. Registered Office. The registered office of the corporation
shall be in the city of Dover, County of Kent, State of Delaware.

         Section 2. Other Offices. The corporation may also have offices at such
other place or places, both within and without the State of Delaware, as the
board of directors may from time to time determine or the business of the
corporation may require.

                                   ARTICLE II
                             Meeting of Stockholders

         Section 1. Time and Place of Meetings. All meetings of the stockholders
shall be held at such time and place, either within or without of the State of
Delaware, or, if so determined by the board of directors in its sole discretion,
at no place (but rather by means of remote communication) as the board of
directors shall designate and as shall be stated in the notice of the meeting.

         Section 2. Annual Meetings. An annual meeting of the stockholders will
be held at such time as may be determined by the board of directors, at which
meeting the stockholders shall elect a board of directors, and transact such
other business as may properly be brought before such meeting pursuant to these
bylaws and applicable law.

         Section 3. Notice of Annual Meetings. Notice of the annual meeting,
stating the place, if any, date, the means of remote communications, if any, by
which stockholders and proxyholders may be deemed to be present in person and
vote at such meeting and hour of the meeting, shall be given to each stockholder
of record entitled to vote at such meeting not less than 10 nor more than 60
days before the date of the meeting in accordance with applicable law, by or at
the direction of the chairman of the board, the chief executive officer, the
secretary, or other officer or person calling the meeting at the direction of
the board, to each stockholder of record entitled to vote at the meeting. Notice
to stockholders may be given by a form of electronic transmission if consented
to by the stockholders to whom the notice is given. If mailed, such notice will
be deemed to be delivered when deposited in the United States mail, addressed to
the stockholder at the address for such stockholder as it appears on the stock
transfer books of the corporation, with the postage thereto prepaid.

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         Section 4. Special Meetings. Special meetings of the stockholders of
the corporation for any purpose or purposes, unless otherwise prescribed by
statute or by the certificate of incorporation, may be called only by the board
of directors pursuant to a resolution approved by a majority of the whole board
of directors or a committee designated for such purpose by the board of
directors. Such resolution shall state the purpose or purposes of the proposed
special meeting. Business transacted at any special meeting of stockholders
shall be limited to the purposes stated in the resolution. The board of
directors or, in the absence of action by the board of directors, the chairman
of the board shall have the power to determine the date, time and place for any
special meeting of stockholders. Following such determination, it shall be the
duty of the secretary to cause notice to be given to the stockholders entitled
to vote at such meeting, that a meeting will be held at the place, if any, time
and date and in accordance with the record date determined by the board of
directors or the chairman of the board.

         Section 5. Notice of Special Meetings. Notice of a special meeting,
stating the place, if any, date, the means of remote communications, if any, by
which stockholders and proxyholders may be deemed to be present in person and
vote at such meeting and hour of the meeting and the purpose or purposes for
which the meeting is called, shall be given to each stockholder of record
entitled to vote at such meeting not less than 10 nor more than 60 days before
the meeting in accordance with applicable law, by or at the direction of the
chairman of the board, the chief executive officer, the secretary, or other
officer or person calling the meeting at the direction of the board of
directors, to each stockholder of record entitled to vote at the meeting. Notice
to stockholders may be given by a form of electronic transmission if consented
to by the stockholders to whom the notice is given. If mailed, such notice will
be deemed to be delivered when deposited in the United States mail, addressed to
the stockholder at the address for such stockholder as it appears on the stock
transfer books of the corporation, with the postage thereto prepaid.

         Section 6. Quorum. The holders of stock having a majority of the voting
power of the stock entitled to be voted thereat, present in person or
represented by proxy, shall constitute a quorum for the transaction of business
at all meetings of the stockholders. Shares of stock will be counted toward a
quorum if they are either (i) present in person at the meeting or (ii)
represented at the meeting by a valid proxy, whether the instrument granting
such proxy is marked as casting a vote or abstaining, is left blank or does not
empower such proxy to vote with respect to some or all matters to be voted upon
at the meeting. The chair of the meeting shall have the power and the duty to
determine whether a quorum is present at any stockholder meeting.

         Section 7. Conduct of Meetings. Meetings of stockholders shall be
presided over by the chairman of the board of directors or by another chair
designated by the board of directors. The date and time of the opening and the
closing of the polls for each matter upon which the stockholders will vote at a
meeting shall be determined by the chair of the meeting and announced at the
meeting. The board of directors may adopt by resolution such rules and
regulations for the conduct of the meeting of stockholders as it shall deem
appropriate. Except inconsistent with such rules and regulations as adopted by
the board

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of directors, the chair of any meeting of stockholders shall have the exclusive
right and authority to prescribe such rules, regulations and procedures and to
do all such acts as, in the judgment of such chair, are appropriate for the
proper conduct of the meeting. Such rules, regulations or procedures, whether
adopted by the board of directors or prescribed by the chair of the meeting, may
include, without limitation, the following: (i) the establishment of an agenda
or order of business for the meeting; (ii) rules and procedures for maintaining
order at the meeting and the safety of those present; (iii) limitations on
attendance at or participation in the meeting to stockholders of record of the
corporation, their duly authorized and constituted proxies or such other persons
as the chair of the meeting shall determine; (iv) restrictions on entry to the
meeting after the time fixed for the commencement thereof; (v) voting procedures
and (vi) limitations on the time allotted to questions or comments by
participants. Unless and to the extent determined by the board of directors or
the chair of the meeting, meetings of stockholders shall not be required to be
held in accordance with the rules of parliamentary procedure.

         Section 8. Adjournment of Meeting. Any meeting of stockholders, annual
or special, may be adjourned solely by the chair of the meeting from time to
time to recovene at the same or some other time, date and place, if aplicable.
The stockholders present at a meeting shall not have authority to adjourn the
meeting. Notice need not be given of any such adjourned meeting if the time,
date and place, if any, thereof and the means of remote communications, if any,
by which the stockholders and proxy holders may be deemed to be present in
person and vote at such adjourned meeting are announced at the meeting at which
the adjournment is taken. If the time, date and place, if any, of the adjourned
meeting are not announced at the meeting at which the adjournment is taken, if
the adjournment is for more than thirty (30) days or if after the adjournment a
new record date is fixed for the adjourned meeting, then the secretary shall
give notice of the adjourned meeting as provided in Section 3 or Section 5 of
this Article II, as appropriate, not less than ten (10) days prior to the date
of the adjourned meeting.

         Section 9. New Business. At an annual meeting of stockholders, only
such new business shall be conducted, and only such proposals shall be acted
upon, as shall have been properly brought before the annual meeting of
stockholders (a) by, or at the direction of, the board of directors or (b) by a
stockholders of the corporation who complies with the procedures set forth in
this Section 9. For new business or any proposal to be properly brought before
an annual meeting of stockholders by a stockholder, the stockholder must have
given proper and timely notice thereof in writing to the secretary of the
corporation and any such proposed business must constitute a proper matter for
stockholder action. To be timely, a stockholder's notice must be delivered to or
mailed and received at the principal executive offices of the corporation not
later than the close of business on the date that is 120 days prior to the first
anniversary of the date the corporation's proxy statement was released to
stockholders in connection with the previous year's annual meeting of
stockholders, provided, however, that in the event that no annual meeting was
held in the previous year or the date of the annual meeting has been changed by
more than 30 days from the date contemplated at the time of the previous year's
proxy statement, notice by the stockholder to be timely must be so received not
later than the close of business on the later of 120 days in advance of

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such annual meeting or 10 days following the date on which public announcement
of the date of the meeting is first made. In no event shall the public
announcement of an adjournment or postponement of an annual meeting commence a
new time period (or extend any time period) for the giving of a stockholder's
notice as described above. A stockholder's notice to the secretary shall set
forth as to each matter the stockholder proposes to bring before the annual
meeting (a) a description, in 500 words or less, of the business desired to be
brought before the annual meeting and the reasons for conducting such business
at the annual meeting, (b) the name and address, as they appear on the
corporation's books, of the stockholder proposing such business, the beneficial
owner, if any, on whose behalf the proposal is made and any other stockholders
known by such stockholder to be supporting such proposal, (c) the class and
number of shares of the stock that are held of record, beneficially owned and
represented by proxy on the date of such stockholder notice and on the record
date of the meeting (if such date shall have been made publicly available) by
the stockholder and by any other stockholders known by such stockholder to be
supporting such proposal on such dates, (d) a representation that the
stockholder is and will continue to be a holder of record of stock of the
corporation entitled to vote at such meeting and intends to appear in person or
by proxy at the meeting to propose such business, (e) any material interest of
the stockholders in such proposal, and (f) all other information that would be
required to be filed with the Securities and Exchange Commission if, with
respect to any such item of business, such stockholder or stockholders were a
participant in a solicitation subject to Section 14 of the Securities Exchange
Act of 1934, as amended (the "Exchange Act").

         The board of directors may reject any stockholder proposal not made
strictly in accordance with the terms of this Section. Alternatively, if the
board of directors fails to consider the validity of any stockholder proposal,
the presiding officer of the annual meeting shall, if the facts warrant,
determine and declare at the annual meeting that the stockholder proposal was
not made in strict accordance with the terms of this section and, if he should
so determine, he shall so declare at the annual meeting and any such business or
proposal not properly brought before the annual meeting shall not be acted upon
at the annual meeting. Notwithstanding the foregoing provisions of this Section
9, if the stockholder (or a qualified representative of the stockholder) does
not appear at the annual meeting of stockholders of the corporation to present
such business, such proposed business shall not be transacted, notwithstanding
that proxies in respect of such vote may have been received by the corporation.

         Notwithstanding the foregoing provisions of this Section 9, a
stockholder shall also comply with all applicable requirements of the Exchange
Act and the rules and regulations thereunder with respect to the matters set
forth in this Section 9. Nothing in this Section 9 shall be deemed to affect any
rights (a) of stockholders to request inclusion of proposals in the
corporation's proxy statement pursuant to Rule 14a-8 under the Exchange Act or
(b) of the holders of any series of Preferred Stock to elect directors pursuant
to any applicable provisions of the corporation's certificate of incorporation.

         Section 10. Voting. Except as otherwise provided in the certificate of
incorporation or any certificate of designation, each stockholder shall, at each
meeting of

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the stockholders, be entitled to one vote in person or by proxy for each share
of stock of the corporation held by him and registered in his name on the books
of the corporation on the date fixed pursuant to the provisions of Section 5 of
Article VII of these bylaws as the record date for the determination of
stockholders who shall be entitled to notice of and to vote at such meeting.
Shares of its own stock belonging to the corporation or to another corporation,
if a majority of the shares entitled to vote in the election of directors of
such other corporation is held directly or indirectly by the corporation, shall
not be entitled to vote nor be counted for quorum purposes; provided, however,
that the foregoing shall not limit the right of the corporation or any
subsidiary of the corporation to vote stock, including, but not limited to, its
own stock held by it in a fiduciary capacity. Any vote by the stockholders of
the corporation may be given at any meeting of stockholders by the stockholder
entitled thereto, in person or by his proxy. Each proxy shall be revocable
unless expressly provided therein to be irrevocable and if, and only as long as,
it is coupled with an interest sufficient in law to support an irrevocable power
or unless otherwise made irrevocable by law. In all matters other than the
election of directors, if a quorum is present, the affirmative vote of the
majority of the votes cast by stockholders in person or represented by proxy at
the meeting and entitled to vote on the subject matter shall be the act of the
stockholders, unless the vote of a greater number is required by these bylaws,
the certificate of incorporation or the General Corporation Law of the State of
Delaware. In determining the number of votes cast for and against a proposal,
shares abstaining from voting on a matter (including withholding votes in
connection with elections) will not be treated as a vote for or against the
proposal. A non-vote by a broker will be treated as if the broker never voted,
but a non-vote by a stockholder will be counted as a vote "for" the management's
position. Where a separate vote by a class or classes or by a series of a class
is required, if a quorum is present, the affirmative vote of the majority of
shares of such class or classes or series of a class present in person or
represented by proxy at the meeting shall be the act of such class or classes or
series of a class. The vote on any question need not be by written ballot. The
stockholders present in person or by proxy at a duly organized meeting may
continue to transact business until adjournment, notwithstanding the withdrawal
of enough stockholders to leave less than a quorum.

         Section 11. List of Stockholders. It shall be the duty of the secretary
or other officers of the corporation who shall have charge of its stock ledger,
either directly or through another officer of the corporation designated by him
or through a transfer agent appointed by the board of directors, to prepare and
make, at least ten days before every meeting of the stockholders, a complete
list of the stockholders entitled to vote thereat, arranged in alphabetical
order, and showing the address of each stockholder and the number of shares
registered in the name of each stockholder. Such list shall be open to the
examination of any stockholder, for any purpose germane to the meeting, as
required by law. If the meeting is to be held at a place, the list shall also be
produced and kept at the time and place of said meeting during the whole time
thereof, and may be inspected by any stockholder of record who shall be present
thereat. If the meeting is to be held solely by means of remote communication,
then the list shall also be open to the examination of any stockholder during
the whole time of the meeting on a reasonably accessible electronic network, and
the information required to access such list shall be

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provided with the notice of the meeting. The stock ledger shall be the only
evidence as to who are the stockholders entitled to examine the stock ledger,
such list or the books of the corporation, or to vote in person or by proxy at
any meeting of stockholders.

         Section 12. Inspectors of Votes. The chairman shall appoint one or more
inspectors to act at each meeting of the stockholders, unless the board of
directors shall have theretofore made such appointments. Each inspector of votes
shall first subscribe an oath or affirmation faithfully to execute the duties of
an inspector of votes at the meeting with strict impartiality and according to
the best of his ability. Such inspectors of votes shall (1) ascertain the number
of shares outstanding and the voting power of each; (2) determine the shares
represented at the meeting and the validity of proxies and ballots; (3) count
all votes and ballots; (4) determine and retain for a reasonable period a record
of the disposition of any challenges made to any determination by the
inspectors; and (5) certify their determination of the number of shares
represented at the meeting, and their count of all votes and ballots. An
inspector of votes need not be a stockholder of the corporation, and any officer
of the corporation may be an inspector of votes on any question other than a
vote for or against his election to any position with the corporation or on any
other question in which he may be directly interested.

         Section 13. Postponement and Cancellation of Meeting. Any previously
scheduled annual or special meeting of the stockholders may be postponed, and
any previously scheduled annual or special meeting of the stockholders called by
the board of directors may be cancelled, by resolution of the board of directors
upon public notice given prior to the time previously scheduled for such meeting
of stockholders.

                                   ARTICLE III
                               Board of Directors

         Section 1. Powers. The business and affairs of the corporation shall be
managed by its board of directors, which shall have and may exercise all powers
of the corporation and take all lawful acts as are not by statute, the
certificate of incorporation or these bylaws directed or required to be
exercised or taken by the stockholders.

         Section 2. Number and Qualification. The number of directors that shall
constitute the whole board of directors shall be determined, from time to time,
only by resolution of the board of directors but shall be no fewer than three
(3) nor more than fifteen (15).

         Section 3. Election and Term of Office. The board of directors shall be
divided into three classes, Class I, Class II and Class III as required by the
Certificate of Incorporation. One class of the directors shall be elected at
each annual meeting of the stockholders. If any such annual meeting is not held
or the directors are not elected thereat, the directors may be elected at any
special meeting of stockholders held for that purpose. All directors shall hold
office until their respective successors are elected and qualified or until
their earlier death, resignation or removal.

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         Section 4. Resignations. Any director may resign at any time by giving
written notice of his resignation to the corporation, effective at the time
specified therein or, if not specified, immediately upon its receipt by the
corporation. Unless otherwise specified in the notice, acceptance of a
resignation shall not be necessary to make it effective.

         Section 5. Nominations. Notwithstanding anything in these bylaws to the
contrary, only persons who are nominated in accordance with the procedures
hereinafter set forth in this Section 5 shall be eligible for election as
directors of the corporation.

         Nominations of persons for election to the board of directors of the
corporation may be made at a meeting of stockholders only (1) by or at the
direction of the board of directors or (2) by any stockholder of record of the
corporation entitled to vote for the election of directors at the meeting at the
time notice is given pursuant to this Section 5 and who complies with the notice
procedures set forth in this Section 5. Such nominations, other than those made
by or at the direction of the board of directors, shall be made pursuant to
timely notice in writing to the secretary of the corporation. To be timely, a
stockholder's notice shall be delivered to or mailed and received at the
principal executive offices of the corporation (y) for annual meetings of
stockholders, not later than the close of business on the one hundred twentieth
day prior to the first anniversary of the date the corporation's proxy statement
was released to stockholders in connection with the preceding year's annual
meeting, or (z) for special meetings at which the board of directors has
determined that directors shall be elected, not later than the close of business
on the one hundred twentieth day prior to such special meeting or the tenth day
following the day on which public announcement is first made of the date of the
special meeting and of the nominees proposed by the board of directors to be
elected at such meeting. Notwithstanding anything in the third sentence of this
paragraph to the contrary, in the event the number of directors to be elected to
the board of directors of the corporation at an annual meeting is increased and
there is no public announcement by the corporation naming the nominees for the
additional directorships at least one hundred twenty days prior to the first
anniversary of the preceding year's annual meeting, a stockholder notice
required by this Section 5 shall also be considered timely, but only with
respect to nominees for the additional directorships, if it shall be delivered
to the secretary at the principal executive offices of the corporation not later
than the close of business on the tenth day following the day on which such
public announcement is first made by the corporation. In no event shall the
public announcement of an adjournment or postponement of an annual meeting
commence a new time period (or extend any time period) for the giving of a new
stockholder's notice as described in this Section 5. Such stockholder's notice
shall set forth: (i) as to each person whom the stockholder proposes to nominate
for election or re-election as a director, all information relating to such
person that is required to be disclosed in solicitations of proxies for election
of directors in an election contest, or is otherwise required, in each case
pursuant to Regulation 14A under the Exchange Act, or any successor regulation
thereto (including such person's written consent to being named in the proxy
statement as a nominee and to serving as a director if elected); and (ii) as to
the stockholder giving the notice and the beneficial owner, if any, on whose
behalf the nomination is made (A) the name and address, as they

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appear on the corporation's books, of such stockholder and of such beneficial
owner, (B) the class and number of shares of the corporation which are
beneficially and of record owned by such stockholder and such beneficial owner,
and (C) a representation that the stockholder is a holder of record of stock of
the corporation entitled to vote at such meeting and intends to appear in person
or by proxy at the meeting to propose such nomination. The corporation may
require any person nominated for election as a director to furnish to the
secretary of the corporation such other information as the corporation may
reasonably require to determine the eligibility of such proposed nominee to
serve as a director of the corporation.

         Except as otherwise provided by law, the Chairman of the meeting shall,
if the facts warrant, determine and declare to the meeting that a nomination was
not made in accordance with the procedures prescribed by this Section 5, and if
he should so determine, he shall so declare to the meeting and the defective
nomination shall be disregarded. Notwithstanding the foregoing provisions of
this Section 5, if the stockholder (or a qualified representative of the
stockholder) does not appear at the annual or special meeting of stockholders of
the corporation to present a nomination, such nomination shall be disregarded,
notwithstanding that proxies in respect of such vote may have been received by
the corporation. Notwithstanding the foregoing provisions of this Section 5, a
stockholder shall also comply with all applicable requirements of the Exchange
Act and the rules and regulations thereunder with respect to the matters set
forth in this Section 5. Nothing in this Section 5 shall be deemed to affect any
rights of the holders of any series of preferred stock to elect directors
pursuant to any applicable provisions of the certificate of incorporation.

         Section 6. Vacancies. Except as otherwise provided by statute or the
certificate of incorporation, in the case of any increase in the number of
directors, such additional director or directors shall be proposed for election
to terms of office that will most nearly result in each class of directors
containing one-third of the entire number of members of the whole board, and,
unless such position is to be filled by a vote of the stockholders at an annual
or special meeting, shall be elected by a majority vote of the directors in such
class or classes, voting separately by class. In the case of any vacancy in the
board of directors, however created, the vacancy or vacancies shall be filled by
majority vote of the directors remaining in the class in which the vacancy
occurs or, if only one such director remains, by such director. In the event one
or more directors shall resign, effective at a future date, such vacancy or
vacancies shall be filled as provided herein. Directors so chosen or elected
shall hold office for the remaining term of the directorship to which appointed.
Any director elected or chosen as provided herein shall serve for the unexpired
term of office or until his successor is elected and qualified or until his
earlier death, resignation or removal.

                       Meetings of the Board of Directors

         Section 7. Time and Place of Meetings. The board of directors of the
corporation may hold meetings, both regular and special, at such time and places
as it determines.

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         Section 8. Annual Meetings. The annual meeting of each newly elected
board of directors may be held at a time convenient to the board of directors.
The first meeting of each newly elected board of directors may be held
immediately following the annual meeting of stockholders, and if so held, no
notice of such meeting to the newly elected directors shall be necessary in
order legally to constitute the meeting, provided a quorum shall be present. If
such meeting is not held immediately following the annual meeting of
stockholders, the meeting may be held at such time and place as shall be
specified in a notice given as hereinafter provided for special meetings of the
board of directors, or as shall be specified in a written waiver signed by all
of the directors.

         Section 9. Regular Meetings - Notice. Regular meetings of the board of
directors may be held without notice.

         Section 10. Special Meetings - Notice. Special meetings of the board of
directors may be called by the chairman of the board, chief executive officer or
any two directors on not less than 15 hours' notice to each director. Notice of
any such meeting need not be given to any director, however, if waived by him in
writing or by telegraph, telex, cable, wireless or other form of recorded
communication, or if he shall be present at the meeting. The purpose or purposes
of any special meeting will be specified in the notice relating thereto.

         Section 11. Quorum and Manner of Acting. At all meetings of the board
of directors, fifty percent (50%) of the directors at the time in office (but
not less than one-third of the whole board of directors) shall constitute a
quorum for the transaction of business, and the act of a majority of the
directors present at any meeting at which a quorum is present shall be the act
of the board of directors, except as may be otherwise specifically provided by
statute or by the certificate of incorporation, or by these bylaws. If a quorum
shall not be present at any meeting of the board of directors, the directors
present may adjourn the meeting from time to time, without notice other than
announcement at the meeting, until a quorum shall be present.

         Section 12. Remuneration. Unless otherwise expressly provided by
resolution adopted by the board of directors, none of the directors shall, as
such, receive any stated remuneration for his services; but the board of
directors may at any time and from time to time by resolution provide that a
specified sum shall be paid to any director of the corporation, either as his
annual remuneration as such director or member of any committee of the board of
directors or as remuneration for his attendance at each meeting of the board of
directors or any such committee. The board of directors may also likewise
provide that the corporation shall reimburse each director for any expenses paid
by him on account of his attendance at any meeting. Nothing in this section
shall be construed to preclude any director from serving the corporation in any
other capacity and receiving remuneration therefor.

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                             Committees of Directors

         Section 13. Committees How Constituted and Powers. The board of
directors may designate one or more committees, each committee to consist of one
or more of the directors of the corporation. The board may designate one or more
directors as alternate members of any committee, who may replace any absent or
disqualified member at any meeting of the committee. Any committee, to the
extent provided in the resolution of the board of directors and not prohibited
by law, shall have and may exercise all the powers and authority of the board of
directors in the management of the business and affairs of the corporation, and
may authorize the seal of the corporation to be affixed to all papers that may
require it. At any meeting of a committee, a majority of the members of the
committee shall constitute a quorum for the transaction of business, and the act
of a majority of the members present at any meeting at which a quorum is present
shall be the act of the committee. In the absence or disqualification of a
member of any committee, the member or members thereof present at any meeting
and not disqualified from voting, whether or not he, she or they constitute a
quorum, may unanimously appoint another member of the board of directors to act
at the meeting in place of any such absent or disqualified member.

         Section 14. Minutes of Committees. Each committee shall keep regular
minutes of its meetings and proceedings and report the same to the board of
directors thereof when requested by the board of directors

                                     General

         Section 15. Actions Without a Meeting. Any action required or permitted
to be taken at any meeting of the board of directors or any committee thereof
may be taken without a meeting, if all members of the board of directors or
committee, as the case may be, consent thereto in writing or by electronic
transmission and the writing or record of electronic transmission are filed with
the minutes of proceedings of the board of directors or the committee.

         Section 16. Presence at Meetings by Means of Communications Equipment.
Members of the board of directors, or of any committee designated by the board
of directors, may participate in a meeting of the board of directors or
committee by means of conference telephone or similar communications equipment
by means of which all persons participating in the meeting can hear one another.
Participation in a meeting conducted pursuant to this section shall constitute
presence in person at the meeting.

         Section 17. Conduct of Meetings. At each meeting of the board of
directors, the chairman of the board, or in the absence of the chairman, a
chairman chosen by the majority of the directors present shall preside.

                                   ARTICLE IV
                                     Notices

         Section 1. Type of Notice. Whenever, under the provisions of the
statutes, the certificate of incorporation or these bylaws, notice is required
to be given to any director,

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it shall not be construed to require personal notice, but such notice may be
given in writing, by mail, addressed to such director, at his address as it
appears on the records of the corporation (unless prior to the mailing of such
notice he shall have filed with the secretary a written request that notices
intended for him be mailed to some other address designated in the request) with
postage thereon prepaid, and such notice shall be deemed to be given at the time
when the same shall be deposited in the United States mail; provided, however,
that, in the case of notice of a special meeting of the board of directors, if
such meeting is to be held within seven calendar days after the date of such
notice, notice shall be deemed given as of the date such notice shall be
accepted for delivery by a courier service that provides "opening of business
next day" delivery, so long as at least one attempt shall have been made, on or
before the date such notice is accepted for delivery by such courier service, to
provide notice by telephone to each director at his principal place of business
and at his principal residence. Notice to directors may also be given by
telegram, telecopier, by personal delivery, telephone or other means of
electronic transmission and shall be deemed given at the time confirmation of
the transmission is obtained by the company.

         Section 2. Waiver of Notice. Whenever any notice is required to be
given under the provisions of any applicable statute, the certificate of
incorporation or these bylaws, a waiver thereof in writing, signed by the person
or persons entitled to said notice or a waiver of notice by electronic
transmission, whether before or after the time stated therein, shall be deemed
equivalent thereto, and transmission of waiver of notice by a director or
stockholder by mail, telegraph, telex, cable, wireless or other form of recorded
communication may constitute such a waiver.

         Section 3. Authorized Notices. Unless otherwise specified herein, the
secretary or such other person or persons as the chief executive officer
designates shall be authorized to give notices for the corporation.

                                    ARTICLE V
                                    Officers

         Section 1. Description. The elected officers of the corporation shall
be a president (who shall be a director), one or more vice presidents, with or
without such descriptive titles as the board of directors shall deem
appropriate, a secretary, a treasurer, and a controller and, if the board of
directors so elects, a chairman of the board (who shall be a director). The
board of directors by resolution shall also appoint one or more assistant
secretaries, assistant treasurers, assistant controllers and such other officers
and agents as from time to time may appear to be necessary or advisable in the
conduct of the affairs of the corporation. Any two or more offices may be held
by the same person.

         Section 2. Election. The board of directors at its first meeting after
each annual meeting of stockholders shall elect and appoint the officers to fill
the positions designated in Section 1 of this Article V.

                                       11
<PAGE>

         Section 3. Salaries. The board of directors shall fix all salaries of
all elected officers of the corporation.

         Section 4. Term. An officer of the corporation shall hold office until
he resigns or his successor is chosen and qualified. Any officer elected or
appointed by the board of directors may be removed at any time by the
affirmative vote of a majority of the whole board of directors. The board of
directors shall fill any vacancy occurring in any office of the corporation by
death, resignation, removal or otherwise.

         Section 5. Duties of the Chairman. The chairman of the board shall
preside when present at all meetings of the board of directors. He shall advise
and counsel the president and other officers of the corporation, and shall
exercise such powers and perform such duties as shall be assigned to or required
of him from time to time by the board of directors.

         Section 6. Duties of the President and Chief Executive Officer. The
president shall be the chief executive officer of the corporation, and, subject
to the provisions of these bylaws, shall have general supervision of the affairs
of the corporation and shall have general and active control of all its
business. He shall have general authority to execute bonds, deeds and contracts
in the name of the corporation and to affix the corporate seal thereto; to sign
stock certificates; to cause the employment or appointment of such employees and
agents of the corporation as the proper conduct of operations may require, and
to fix their compensation, subject to the provisions of these bylaws; to remove
or to suspend any employee or agent who shall have been employed or appointed
under his authority or under authority of an officer subordinate to him; to
suspend for cause, pending final action by the authority that shall have elected
or appointed him, any officer subordinate to the president, and, in general, to
exercise all the powers usually appertaining to the office of president of a
corporation, except as otherwise provided in these bylaws. In the absence of the
president, his duties shall be performed and his powers may be exercised by such
other officer as he shall designate in writing or (failing such designation) by
the executive committee (if any has been appointed) or such officer as it shall
designate in writing, subject, in either case, to review and superseding action
by the board of directors.

         Section 7. Duties of the Vice President-Finance. There may be
designated a vice president finance, who, if so designated, shall be the chief
financial and accounting officer of the corporation. He shall have active
control of and responsibility for all matters pertaining to the financial
affairs of the corporation and its subsidiaries. His authority shall include the
authorities of the treasurer and controller. He shall be responsible for
approval of all filings with governmental agencies. He shall have the authority
to execute and deliver bonds, deeds, contracts and stock certificates of and for
the corporation, and to affix the corporate seal thereto by handwritten or
facsimile signature and all other powers customarily appertaining to his office,
except to the extent otherwise limited or enlarged. He shall report to the
president and to the executive committee and the board of directors of the
corporation at their request on all financial matters of the corporation.

                                       12
<PAGE>

         Section 8. Duties of Vice Presidents and Assistant Vice Presidents. In
the absence of the president or in the event of his inability or refusal to act,
the vice president (or in the event there be more than one vice president, the
vice presidents in the order designated by the board, or in the absence of any
designation, in the order of their election) shall perform the duties of the
president and, when so acting, shall have all the powers of and be subject to
all the restrictions upon the president. The vice presidents shall perform such
other duties and have such other powers as the board of directors or the
president may from time to time prescribe.

         Section 9. Duties of Secretary and Assistant Secretaries. The secretary
or an assistant secretary shall attend all meetings of the board of directors
and all meetings of the stockholders and record all proceedings of the meetings
of the stockholders of the corporation and of the board of directors in a book
to be kept for that purpose, and shall perform like duties for the standing
committees when required. The secretary shall be under the supervision of the
president and shall perform such other duties as may be prescribed by the
president. The secretary shall have charge of the seal of the corporation and
have authority to affix the seal to any instrument requiring it. When so
affixed, the seal shall be attested by the signature of the secretary or
treasurer or an assistant secretary or assistant treasurer, which may be a
facsimile. The secretary shall keep and account for all books, documents, papers
and records of the corporation except those for which some other officer or
agent is properly accountable. The secretary shall have authority to sign stock
certificates, and shall generally perform all the duties appertaining to the
office of the secretary of a corporation.

         Assistant secretaries in the order of their seniority, unless otherwise
determined by the board of directors, shall assist the secretary, and in the
absence or disability of the secretary, perform the duties and exercise the
powers of the secretary. They shall perform such other duties and have such
other powers as the board of directors may from time to time prescribe.

         Section 10. Duties of Treasurer and Assistant Treasurers. The treasurer
shall have the responsibility for and custody over all assets of the
corporation, and the responsibility for handling of the liabilities of the
corporation. He shall cause proper entries of all receipts and disbursements of
the corporation to be recorded in its books of account. He shall have the
responsibility for all matters pertaining to taxation and insurance. He shall
have the authority to endorse for deposit or collection, or otherwise, all
commercial paper payable to the corporation, and to give proper receipts or
discharges for all payments to the corporation. He shall be responsible for all
terms of credit granted by the corporation and for the collection of all its
accounts. He shall have the authority to execute and deliver bonds, deeds,
contracts and stock certificates of and for the corporation, and to affix the
corporate seal thereto by handwritten or facsimile signature and all other
powers customarily appertaining to his office, except to the extent otherwise
limited or enlarged. The treasurer shall be under the supervision of the vice
president-finance and he shall perform such other duties as may be prescribed to
him by the vice president-finance, if one be designated.

                                       13
<PAGE>

         Assistant treasurers, in the order of their seniority, shall assist the
treasurer, and in the absence or disability of the treasurer, perform the duties
and exercise the powers of the treasurer.

         Section 11. Duties of Controller and Assistant Controllers. The
controller shall be responsible for all matters pertaining to the accounts of
the corporation, its subsidiaries and divisions, with the supervision of the
books of account, their installation, arrangement and classification. The
controller shall maintain adequate records of all assets, liabilities and
transactions; see that an adequate system of internal audit thereof is currently
and regularly maintained; coordinate the efforts of the corporation's
independent public accountants in its external audit program; receive, review
and consolidate all operating and financial statements of the corporation and
its various departments and subsidiaries; and prepare financial statements,
reports and analyses. The controller shall have supervision of the accounting
practices of the corporation and of each subsidiary and division of the
corporation, and shall prescribe the duties and powers of the chief accounting
personnel of the subsidiaries and divisions. The controller shall cause to be
maintained an adequate system of financial control through a program of budgets,
financial planning and interpretive reports. The controller shall initiate and
enforce accounting measures and procedures whereby the business of the
corporation and its subsidiaries and divisions shall be conducted with the
maximum efficiency and economy. The controller shall have all other powers
customarily appertaining to the office of controller, except to the extent
otherwise limited or enlarged. The controller shall be under the supervision of
the vice president-finance, if one be designated.

         The assistant controllers, in the order of their seniority, shall
assist the controller, and if the controller is unavailable, perform the duties
and exercise the powers of the controller.

                                   ARTICLE VI
                                 Indemnification

         Section 1. Damages and Expenses. (a) The corporation shall indemnify
every person (including such person's heirs, executors and administrators) who
is or was a party or is or was threatened to be made a party to any threatened,
pending or completed action, suit, or proceeding, whether civil, criminal,
administrative or investigative, by reason of the fact that he is or was a
director, officer, employee or agent of the corporation or any of its direct or
indirect wholly-owned subsidiaries or, while a director, officer, employee or
agent of the corporation or any of its direct or indirect wholly-owned
subsidiaries, is or was serving at the request of the corporation or any of its
direct or indirect wholly-owned subsidiaries, as a director, officer, employee,
agent or trustee of another corporation, partnership, joint venture, trust,
employee benefit plan or other enterprise, against expenses (including counsel
fees), judgments, fines, penalties, other liabilities and amounts paid in
settlement actually and reasonably incurred by him in connection with such
action, suit or proceeding, to the full extent permitted by applicable laws,
provided that the corporation shall not be obligated to indemnify any such
person against any such action, suit or proceeding which is brought by such
person against the

                                       14
<PAGE>

corporation or any of its direct or indirect wholly-owned subsidiaries or the
directors of the corporation or any of its direct or indirect wholly-owned
subsidiaries, other than an action brought by such person to enforce his rights
to indemnification hereunder, unless the board of directors of the corporation
shall have previously approved the bringing of such action, suit or proceeding.
The corporation shall indemnify every person who is or was a party or is or was
threatened to be made a party to any action, suit, or proceeding, whether civil,
criminal, administrative or investigative, by reason of the fact that he is or
was licensed to practice law and an employee (including an employee who is or
was an officer) of the corporation or any of its direct or indirect wholly-owned
subsidiaries and, while acting in the course of such employment committed or is
alleged to have committed any negligent acts, errors or omissions in rendering
professional legal services at the request of the corporation or pursuant to his
employment (including, without limitation, rendering written or oral legal
opinions to third parties) against expenses (including counsel fees), judgments,
fines, and amounts paid in settlement actually and reasonably incurred by him in
connection with such action, suit or proceeding, to the full extent permitted by
applicable law. The termination of any action, suit or proceeding by judgment,
order, settlement, conviction or upon a plea of nolo contendere or its
equivalent, shall not, of itself, create a presumption that such person did not
act in good faith and in a manner which he reasonably believed to be in or not
opposed to the best interests of the corporation, and, with respect to any
criminal action or proceeding, has reasonable cause to believe that his conduct
was unlawful.

         (b) Expenses incurred by an officer or director of the corporation or
any of its direct or indirect wholly-owned subsidiaries in defending a civil or
criminal action, suit or proceeding shall be paid by the corporation in advance
of the final disposition of such action, suit or proceeding upon receipt of an
undertaking by or on behalf of such director or officer to repay such amount if
it shall ultimately be determined that he is not entitled to be indemnified by
the corporation as authorized in this Section 1. Such expenses incurred by other
employees and agents may be so paid upon such terms and conditions, if any, as
the board of directors deems appropriate.

         (c) The indemnification and advancement of expenses provided by, or
granted pursuant to, this Section 1 shall not be deemed exclusive of any other
rights to which those seeking indemnification or advancement of expenses may be
entitled under any provision of law, the corporation's certificate of
incorporation, the certificate of incorporation or bylaws or other governing
documents of any direct or indirect wholly-owned subsidiary of the corporation,
or any agreement, vote of stockholders or disinterested directors or otherwise,
both as to action in his official capacity and as to action in another capacity
while holding any of the positions or having any of the relationships referred
to in this Section 1.

         Section 2. Prepaid Expenses. Subject in all respects to Section 1(b)
above of this Article VI, expenses incurred in defending a civil or criminal
action, suit or proceeding may be paid by the corporation in advance of the
final disposition of such action, suit or proceeding, as authorized by the board
of directors in the specific case.

                                       15
<PAGE>

         Section 3. Insurance. The corporation may purchase and maintain
insurance on behalf of any person who is or was a director, officer, employee or
agent of the corporation, or is or was serving at the request of the corporation
as a director, officer, employee or agent of another corporation, partnership,
joint venture, trust or other enterprise against any liability asserted against
him and incurred by him in any such capacity, or arising out of his status as
such, whether or not the corporation would have the power to indemnify him
against such liability under the provisions of this Article VI.

         Section 4. Mergers. For purposes of this Article VI, references to "the
corporation" shall include, in addition to the resulting or surviving
corporation, constituent corporations (including any constituent of a
constituent) absorbed in a consolidation or merger that, if its separate
existence had continued, would have had power and authority to indemnify its
directors, officers, employees or agents, so that any person who is or was a
director, officer, employee or agent of such constituent corporation or is or
was serving at the request of such constituent corporation as a director,
officer, employee or agent of another corporation, partnership, joint venture,
trust or other enterprise shall stand in the same position under the provisions
of this Article VI with respect to the resulting or surviving corporation as he
would have with respect to such constituent corporation if its separate
existence had continued.

         Section 5. Suits for Indemnification. If a claim for indemnification or
advancement of expenses under this Article VI is not paid in full within thirty
(30) days after a written claim therefor by the person seeking indemnification
or reimbursement or advancement of expenses has been received by the
corporation, the person may file suit to recover the unpaid amount of such claim
and, if successful, in whole or in part, shall be entitled to be paid the
expenses of prosecuting such claim.

         Section 6. Offsets to Indemnification. The corporation's obligation, if
any, to indemnify or to advance expenses to any person who was serving at its
request as a director, officer, employee or agent of another corporation,
partnership, joint venture, trust, enterprise or nonprofit entity shall be
reduced by any amount such person may collect as indemnification or advancement
of expenses from such other corporation, partnership, joint venture, trust,
enterprise or non-profit entity.

                                   ARTICLE VII
                         Certificates Representing Stock

         Section 1. Rights to Certificate. Every holder of stock in the
corporation shall be entitled to have a certificate, signed by, or in the name
of the corporation by, the chairman of the board, the president or a vice
president and by the secretary or an assistant secretary of the corporation,
certifying the number of shares owned by him in the corporation. If the
corporation shall be authorized to issue more than one class of stock or more
than one series of any class, the powers, designations, preferences and
relative, participating, option or other special rights of each class of stock
or series thereof and the qualifications, limitations or restrictions of such
preferences or rights shall be set forth in full or summarized on the face or
back of the certificate that the

                                       16
<PAGE>

corporation shall issue to represent such class or series of stock; provided,
that, except as otherwise provided in Section 202 of the General Corporation Law
of the State of Delaware, in lieu of the foregoing requirements, there may be
set forth on the face or back of the certificate that the corporation shall
issue to represent such class or series of stock a statement that the
corporation will furnish without charge to each stockholder who so requests the
powers, designations, preferences and relative, participating, optional or other
special rights of each class of stock or series thereof and the qualifications,
limitations or restrictions of such preferences or rights.

         Section 2. Facsimile Signatures. Any or all of the signatures on the
certificate may be facsimile. In case any officer, transfer agent or registrar
who has signed or whose facsimile signature has been placed upon a certificate
shall have ceased to be such officer, transfer agent or registrar before such
certificate is issued, it may be issued by the corporation with the same effect
as if he were such officer, transfer agent or registrar at the date of issue.

         Section 3. New Certificates. The board of directors may direct a new
certificate or certificates to be issued in place of any certificate or
certificates theretofore issued by the corporation and alleged to have been
lost, stolen or destroyed, upon the making of an affidavit of that fact by the
person claiming the certificate of stock to be lost, stolen or destroyed. When
authorizing such issue of a new certificate or certificates, the board of
directors may, in its discretion and as a condition precedent to the issuance
thereof, require the owner of such lost, stolen or destroyed certificate or
certificates, or his legal representative, to advertise the same in such manner
as it shall require or to give the corporation a bond in such sum as it may
direct as indemnity against any claim that may be made against the corporation
with respect to the certificate alleged to have been lost, stolen or destroyed
or the issuance of such new certificate.

         Section 4. Transfers. Upon surrender to the corporation or the transfer
agent of the corporation of a certificate for shares duly endorsed or
accompanied by proper evidence of succession, assignation or authority to
transfer, it shall be the duty of the corporation, subject to any proper
restrictions on transfer, to issue a new certificate to the person entitled
thereto, cancel the old certificate and record the transaction upon its books.

         Section 5. Record Date. The board of directors may fix, in advance, a
record date, which record date shall not precede the date upon which the
resolution fixing the record date is adopted by the board of directors, which
(i) in the case of determination of stockholders entitled to vote at any meeting
of stockholders or adjournment thereof, shall, unless otherwise required by law,
not be fewer than 10 nor more than 60 days before the date of the meeting, and
(ii) in the case of any other lawful action, shall not be more than sixty (60)
days prior to such action. If there is no record date fixed by the board of
directors (i) the record date for determining stockholders entitled to notice of
or to vote at a meeting of stockholder shall be the close of business on the day
next preceding the day on which notice is given, or, if notice is waived, at the
close of business on the day next preceding the day on which the meeting is
held, and (ii) the record date for determining

                                       17
<PAGE>

stockholders for any other purpose shall be at the close of business on the day
on which the board of directors adopts the resolution relating thereto. A
determination of stockholders of record entitled to notice of or to vote at a
meeting of stockholders shall apply to any adjournment of the meeting; provided,
however, that the board of directors may fix a new record date for the adjourned
meeting.

         Section 6. Registered Stockholders. The corporation shall be entitled
to recognize the exclusive right of a person registered on its books as the
owner of shares to receive dividends and to vote as such owner, and shall not be
bound to recognize any equitable or other claim to or interest in such share or
shares on the part of any other person, whether or not provided by the laws of
the State of Delaware.

                                  ARTICLE VIII
                               General Provisions

         Section 1. Dividends. Dividends upon the capital stock of the
corporation, if any, may be declared by the board of directors pursuant to law.
Dividends may be paid in cash, in property, or in shares of the capital stock or
other securities.

         Section 2. Reserves. Before payment of any dividend, there may be set
aside out of any funds of the corporation available for dividends such sum or
sums as the board of directors from time to time, in their absolute discretion,
thinks proper as a reserve or reserves to meet contingencies, or for equalizing
dividends, or for repairing or maintaining any property of the corporation, or
for such other purpose as the board of directors shall think conducive to the
interest of the corporation, and the board of directors may modify or abolish
any such reserve in the manner in which it was created.

         Section 3. Annual Statement. The board of directors shall present at
each annual meeting, and at any special meeting of the stockholders when called
for by vote of the stockholders, a full and clear statement of the business and
condition of the corporation.

         Section 4. Checks. All checks or demands for money and promissory notes
of the corporation shall be signed by such officer or officers or such other
person or persons as the board of directors may from time to time prescribe.

         Section 5. Corporate Contracts and Instruments. The president, any vice
president, the secretary or the treasurer may enter into contracts and execute
instruments on behalf of the corporation. The board of directors, the president
or any vice president may authorize any officer or officers, and any employee or
employees or agent or agents of the corporate or any of its subsidiaries, to
enter into any contract or execute any instrument in the name of and on behalf
of the corporation, and such authority may be general or confined to specific
instances.

         Section 6. Fiscal Year. The fiscal year of the corporation shall end
December 31 of each year, unless subsequently redetermined by the board of
directors.

                                       18
<PAGE>

         Section 7. Corporate Seal. The corporate seal shall have inscribed
thereon the name of the corporation, the year of its organization, and the word
"Delaware." The seal may be used by causing it or a facsimile thereof to be
impressed, affixed, reproduced or otherwise.

         Section 8. Certificate of Incorporation. These bylaws are subject to
the terms of the certificate of incorporation of the corporation.

                                   ARTICLE IX
                                   Amendments

         Section 1. Amendment by Directors. Except any amendment to this Article
IX and to Article II, Section 4, Article III, Section 3, Article III, Section 6,
Article VI, Section 1 and Article IV, Section 1 of these bylaws, or any of such
provisions, which shall require approval by the affirmative vote of directors
representing at least 75% of the number of directors provided for in accordance
with Article III, Section 2, and except as otherwise expressly provided in a
bylaw adopted by the stockholders, the directors, by the affirmative vote of a
majority of the whole board and without the assent or vote of the stockholders,
may at any meeting, make, repeal, alter, amend or rescind any of these bylaws,
provided the substance of the proposed amendment or other action shall have been
stated in a notice of the meeting.

                                       19<PAGE>
                                                                     EXHIBIT 4.7

ITEM 1. DESCRIPTION OF SECURITIES TO BE REGISTERED

     On April 21, 1999, Input/Output, Inc. (the "Company") and Harris Trust and
Savings Bank, as Rights Agent (the "Rights Agent") entered into the First
Amendment ("Amendment No. 1") to the Rights Agreement (the "Rights Agreement"),
dated as of January 17, 1997, by and between the Company and the Rights Agent.

     On January 17, 1997, the Board of Directors of the Company declared a
dividend distribution of one Right for each outstanding share of the Company's
common stock, $0.01 par value (the "Common Stock"), to stockholders of record at
the close of business on January 27, 1997. Each Right entitles the registered
holder to purchase from the Company one one-thousandth (1/1,000) of a share of
Series A Preferred Stock, par value $0.01 per share (the "Preferred Stock"), at
a Purchase Price of $200 per one one-thousandth (1/1,000) of a share, subject to
adjustment. The description and terms of the Rights are set forth in a Rights
Agreement between the Company and the Rights Agent.

     Initially, the Rights will be attached to all Common Stock certificates
representing shares then outstanding, and no separate Rights Certificates will
be distributed. The Rights will separate from the Common Stock upon the earlier
of (i) the date of a public announcement by the Company that a person or group
of affiliated or associated persons (an "Acquiring Person") has acquired, or
obtained the right to acquire, beneficial ownership of twenty percent (20%) or
more of the outstanding shares of Common Stock (the "Stock Acquisition Date"),
or (ii) ten (10) business days (or such later date as the Board of Directors
shall determine) following the commencement of a tender or exchange offer that
would result in a person or group beneficially owning twenty percent (20%) or
more of such outstanding shares of Common Stock. The date the Rights separate is
referred to as the "Distribution Date."

     Until the Distribution Date, (i) the Rights will be evidenced by the Common
Stock certificates and will be transferred only with such Common Stock
certificates, (ii) new Common Stock certificates issued after January 27, 1997
will contain a notation incorporating the Rights Agreement by reference, and
(iii) the surrender for transfer of any certificates for Common Stock
outstanding will also constitute the transfer of the Rights associated with the
Common Stock represented by such certificates.

     The Rights are not exercisable until the Distribution Date and will expire
at the close of business on January 27, 2007, unless earlier redeemed by the
Company as described below.

     As soon as practicable after the Distribution Date, Rights Certificates
will be mailed to holders of record of the Common Stock as of the close of
business on the Distribution Date and, thereafter, the separate Rights
Certificates will represent the Rights. Except in connection with shares of
Common Stock issued or sold pursuant to the exercise of stock options or under
any employee plan or arrangements, or upon the exercise, conversion or exchange
of securities hereinafter issued by the Company, or as otherwise determined by
the Board of Directors, only shares of Common Stock issued prior to the
Distribution Date will be issued with Rights. In the event that (i) the Company
is the surviving corporation in a merger or other business combination with an
Acquiring Person (or any associate or affiliate thereof) and its Common Stock
remains outstanding

<PAGE>

and unchanged, (ii) any person shall acquire beneficial ownership of more than
twenty percent (20%) of the outstanding shares of Common Stock (except pursuant
to certain consolidations or mergers involving the Company or sales or transfers
of the combined assets, cash flow or earning power of the Company and its
subsidiaries), or (iii) there occurs a reclassification of securities, a
recapitalization of the Company or any of certain business combinations or other
transactions (other than certain consolidations and mergers involving the
Company and sales or transfers of the combined assets, cash flow or earning
power of the Company and its subsidiaries) involving the Company or any of its
subsidiaries which has the effect of increasing by more than one percent (1%)
the proportionate share of any class of the outstanding equity securities of the
Company or any of its subsidiaries beneficially owned by an Acquiring Person (or
any associate or affiliate thereof), each holder of a Right (other than the
Acquiring Person and certain related parties) will thereafter have the right to
receive, upon exercise, Common Stock (or, in certain circumstances, cash,
property or other securities of the Company) having a value equal to two times
the Purchase Price of the Right. Notwithstanding any of the foregoing, following
the occurrence of any of the events described in this paragraph, all Rights that
are, or (under certain circumstances specified in the Rights Agreement) were,
beneficially owned by any Acquiring Person will be null and void.

     In the event that, at any time following the Stock Acquisition Date, (i)
the Company shall enter into a merger or other business combination transaction
in which the Company is not the surviving corporation, (ii) the Company is the
surviving corporation in a consolidation, merger or similar transaction pursuant
to which all or part of the outstanding shares of Common Stock are changed into
or exchanged for stock or other securities of any other person or cash or any
other property or (iii) more than 50% of the combined assets, cash flow or
earning power of the Company and its subsidiaries is sold or transferred (in
each case other than certain consolidations with, mergers with and into, or
sales of assets, cash flow or earning power by or to subsidiaries of the Company
as specified in the Rights Agreement), each holder of a Right (except Rights
which previously have been voided as set forth above) shall thereafter have the
right to receive, upon exercise, common stock of the acquiring company having a
value equal to two times the Purchase Price of the Right. The events described
in this paragraph and in the preceding paragraph are referred to as the
"Triggering Events."

     The Purchase Price payable, the number and kind of shares covered by each
Right and the number of Rights outstanding are subject to adjustment from time
to time to prevent dilution (i) in the event of a stock dividend on, or a
subdivision, combination or reclassification of, the Preferred Stock, (ii) if
holders of the Preferred Stock are granted certain rights, options or warrants
to subscribe for Preferred Stock or securities convertible into Preferred Stock
at less than the current market price of the Preferred Stock, or (iii) upon the
distribution to holders of the Preferred Stock of evidences of indebtedness,
cash (excluding regular quarterly cash dividends), assets (other than dividends
payable in Preferred Stock) or subscription rights or warrants (other than those
referred to in (ii) immediately above).

     With certain exceptions, no adjustment in the Purchase Price will be
required until cumulative adjustments amount to at least one percent (1%) of the
Purchase Price. No fractional shares of Preferred Stock are required to be
issued (other than fractions which are integral multiples of one one-thousandth
(1/1,000) of a share of Preferred Stock) and, in lieu thereof, the Company may
make an adjustment in cash based on the market price of the Preferred Stock on
the trading date immediately prior to the date of exercise.

                                       2
<PAGE>

     At any time after any person or group becomes an Acquiring Person and prior
to the acquisition by such person or group of fifty percent (50%) or more of the
outstanding shares of Common Stock, the Board of Directors of the Company may,
without payment of the Purchase Price by the holder, exchange the Rights (other
than Rights owned by such person or group, which will become void), in whole or
in part, for shares of Common Stock at an exchange ratio of one-half (1/2) the
number of shares of Common Stock (or in certain circumstances, Preferred Stock)
for which a Right is exercisable immediately prior to the time of the Company's
decision to exchange the Rights (subject to adjustment).

     At any time following the Stock Acquisition Date, the Company may redeem
the Rights in whole, but not in part, at a price of $0.001 per Right (payable in
cash, shares of Common Stock or other consideration deemed appropriate by the
Board of Directors). Immediately upon the action of the Board of Directors
ordering redemption of the Rights, the Rights will terminate and the only right
of the holders of Rights will be to receive the $0.001 redemption price.

     The term "Disinterested Director" means any member of the Board of
Directors of the Company who was a member of the Board prior to the date of the
Rights Agreement, and any person who is subsequently elected to the Board if
such person is recommended or approved by a majority of the Disinterested
Directors, but shall not include an Acquiring Person, or an affiliate or
associate of an Acquiring Person, or any representative of the foregoing
entities.

     Until a Right is exercised, the holder thereof, as such, will have no
rights as a stockholder of the Company, including, without limitation, the
right to vote or to receive dividends. While it is expected that under current
federal income tax law, the distribution of the Rights will not be taxable to
stockholders or to the Company, stockholders may, depending upon the
circumstances, recognize taxable income in the event that the Rights become
exercisable for Common Stock (or other consideration) of the Company or for
common stock of an acquiring company as set forth above or in the event that the
Rights are redeemed.

     Other than those provisions relating to the principal economic terms of the
Rights, any of the provisions of the Rights Agreement may be amended by the
Board of Directors of the Company prior to the Distribution Date; PROVIDED, that
any amendments after the Stock Acquisition Date must be approved by a majority
of the Disinterested Directors. After the Distribution Date, the provisions of
the Rights Agreement may be amended by the Board in order to cure any ambiguity,
inconsistency or defect, to make changes which do not adversely affect the
interest of holders of Rights (excluding the interest of any Acquiring Person)
or to shorten or lengthen any time period under the Rights Agreement; PROVIDED,
HOWEVER, that no amendment to adjust the time period governing redemption shall
be made at such time as the Rights are not redeemable.

     A copy of the Rights Agreement has been filed with the Securities and
Exchange Commission as an Exhibit to a Registration Statement on Form 8-A filed
on January 27, 1997. A copy of the Rights Agreement is available free of charge
from the Rights Agent. This summary description of the Rights does not purport
to be complete and is qualified in its entirety by reference to the Rights
Agreement, which is incorporated herein by reference.

                                       3
<PAGE>

     Amendment No. 1 provides that notwithstanding any provision to the contrary
contained in the Rights Agreement, neither SCF-IV, L.P., a Delaware limited
partnership ("SCF-IV"), nor any of its affiliates shall be deemed to be an
Acquiring Person as a result of any combination of the following actions: (i)
the execution and delivery of the Purchase Agreement, dated as of April 21,
1999, by and between the Company and SCF-IV (the "Purchase Agreement"); (ii) the
acquisition of shares of the Company's Series B Preferred Stock, $0.01 par value
per share (the "Series B Preferred Stock"), and/or the Company's Series C
Preferred Stock, $0.01 par value per share (the "Series C Preferred Stock"), in
accordance with the terms of the Purchase Agreement; (iii) the acquisition of
shares of Common Stock of the Company upon conversion of the shares of Series B
Preferred Stock or Series C Preferred Stock; (iv) the acquisition of securities
of the Company in accordance with the Purchase Agreement (including any Common
Stock issuable upon conversion, exercise or exchange thereof); or (v) an
acquisition of additional shares of Common Stock of the Company to the extent
permitted by the terms of the Purchase Agreement.

     In addition, Amendment No. 1 provides that in no event shall a Stock
Acquisition Date or a Distribution Date (both as defined under the Rights
Agreement) be deemed to occur as a result of (i) the execution and delivery of
the Purchase Agreement by SCF-IV and the Company, (ii) the acquisition by
SCF-IV of shares of Series B Preferred Stock and/or Series C Preferred Stock of
the Company in accordance with the terms of the Purchase Agreement, (iii) the
acquisition by SCF-IV of shares of Common Stock of the Company upon conversion
of the shares of Series B Preferred Stock or Series C Preferred Stock, (iv) the
acquisition by SCF-IV of securities of the Company in accordance with the terms
of the Purchase Agreement (including any Common Stock issuable upon conversion,
exercise or exchange thereof), or (v) the acquisition by SCF-IV of additional
shares of Common Stock of the Company to the extent permitted by the terms of
the Purchase Agreement. Amendment No. 1 further amends the Rights Agreement to
include several definitions.

     The Company has agreed that it will not further amend the Rights Agreement
or adopt any similar agreement, that conflicts with, or restricts SCF-IV to a
greater extent than the provisions contained in the Purchase Agreement.

                                       4

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