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                                                                     EXHIBIT 4.2

                          STOCK OPTION GRANT AGREEMENT
                         UNDER GX TECHNOLOGY CORPORATION
                              EMPLOYEE STOCK OPTION
                                      PLAN

         THIS AGREEMENT is entered into this ____ day of _______, 2004, between
Input/Output, Inc., a Delaware corporation (the "Company"), and _____________,
an employee of the Company ("Grantee"), pursuant to the provisions of the GX
Technology Corporation Employee Stock Option Plan (Effective March 4, 2004) (as
amended, the "Plan").

         WHEREAS, on May 10, 2004, the Company entered into a Stock Purchase
Agreement (the "Purchase Agreement") with GX Technology Corporation, a Texas
corporation ("GXT"), pursuant to which the Company has acquired all of the
issued and outstanding capital stock of GXT;

         WHEREAS, in connection with transactions contemplated under the
Purchase Agreement, the Company has assumed the Plan and all of the outstanding
stock options granted under the Plan and the Company shall be successor to GXT
under the Plan for all purposes;

         WHEREAS, this Agreement and Option are intended to evidence and
continue the balance of stock options previously granted to Grantee under the
Plan on _____________ ("Grant Date") (not otherwise cancelled or forfeited) to
reflect the conversion price and the number of shares for which such stock
options are continued and exercisable into after giving effect to the Purchase
Agreement; and

         WHEREAS, the Committee has authorized and approved the grant and
continuation of this Option to Grantee which shall be a nonstatutory stock
option subject to the terms and conditions provided herein.

         NOW, THEREFORE, in consideration of the mutual covenants contained
herein, the parties do hereby agree as follows:

         1. SECTION 1. GRANT OF OPTION. Subject to all of the terms, conditions
and provisions of the Plan and of this Agreement, the Company hereby grants to
Grantee an option (the "Option") under the Plan pursuant to which Grantee shall
have the right and option under the Plan to purchase from the Company all or any
part of an aggregate of ________ shares of the Common Stock of the Company, par
value $0.01 per share (the "Option Shares") which continues the options
previously granted to the Grantee under the Plan prior to the date of the
Purchase Agreement which were not otherwise cancelled or terminated. This Option
shall be a nonstatutory stock option. The Option Shares, when issued to Grantee
upon the exercise of the Option, shall be fully paid and



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nonassessable. This Option is being granted in consideration of the employment
of Grantee with the Company. All capitalized terms used herein shall have the
meanings set forth in the Plan unless otherwise provided herein.

         SECTION 2. OPTION PRICE. The purchase price payable by Grantee to the
Company in exercise of this Option shall be $____ per share (the "Option
Price"). The Option Term shall be from the Grant Date until the tenth (10th)
anniversary of the Grant Date.

         SECTION 3. EXERCISE PERIOD AND EXERCISE OF OPTION. The Options are
vested and are exercisable as to 100% of the Common Stock covered hereby on the
date hereof. Any Option Shares which remain unexcercised on the tenth (10th)
anniversary of the Grant Date shall expire. Unless specifically provided
otherwise in the Plan, the Option may be exercised at any time as long as
Grantee has been continuously employed by the Company, its parent, or a
subsidiary from the Grant Date until the Option is exercised. Other terms and
conditions under which the Option may be exercised are specifically provided in
the Plan.

         SECTION 4. NO EMPLOYMENT COMMITMENT. Grantee acknowledges that neither
the grant of this Option nor the execution of this Agreement by the Company
shall be interpreted or construed as imposing upon the Company an obligation to
retain his services on behalf of the Company or its affiliates for any stated
period of time, which employment shall continue to be at the pleasure of the
Company at such compensation as it shall determine.

         SECTION 5. PLAN. As previously provided, the Option is subject to all
of the terms, conditions and provisions of the Plan. Grantee hereby acknowledges
receipt of a copy of the Plan and the parties agree that the entire text of such
Plan be, and it hereby is, incorporated herein by reference as fully as if here
copied in full. The terms of the Plan shall control with respect to the effect
of Grantee's termination of employment, the adjustments to be made in the event
of changes in the capital structure or other changes of the Company and of all
of the other provisions, terms and conditions of the Plan applicable to the
Option granted herein. If any of the provisions of this Agreement conflict with
the Plan, the provisions of the Plan shall be controlling. The Grantee hereby
agrees to accept as binding, conclusive and final all decisions or
interpretations of the Committee, the Company or the Board, as appropriate, upon
any questions arising under the Plan or this Agreement.

         SECTION 6. NON-TRANSFERABILITY. The Option hereunder is not
transferable or assignable by Grantee except by will or by the laws of descent
and distribution or as otherwise specifically provided in the Plan. No right or
benefit hereunder shall in any manner be liable for or subject to any debts,
contracts, liabilities, obligations or torts of Grantee.

          SECTION 7. NO GUARANTEE OF TAX CONSEQUENCES. The Company and the
Committee make no commitment or guarantee that any federal or state tax
treatment will apply or be available to



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any person eligible for benefits under the Option. The Grantee has been advised
and been provided the opportunity to obtain independent legal and tax advice
regarding this Agreement, the Option and exercise of the Option and the
disposition of any Option Shares acquired thereby.

         SECTION 8. NO RIGHTS IN SHARES. Grantee shall have no rights as a
stockholder in respect of the Shares until the Grantee becomes the record holder
of such Shares.

         SECTION 9. WITHHOLDING OF TAXES.

                  (a) TAX WITHHOLDING. The Company shall have the power and the
right to deduct or withhold, or require an Grantee to remit to the Company, an
amount sufficient to satisfy federal, state, and local taxes, domestic or
foreign, required by law or regulation to be withheld with respect to any
taxable event arising as a result of the Option or its exercise hereunder.

                  (b) SHARE WITHHOLDING. With respect to tax withholding
required upon the exercise of Option Shares, Grantee may elect, subject to the
approval of the Committee in its sole discretion, to satisfy the withholding
requirement, in whole or in part, by having the Company withhold Shares having a
Fair Market Value on the date the tax is to be determined equal to the statutory
total tax which could be imposed on the transaction. All such elections shall be
made in writing, signed by the Grantee, and shall be subject to any restrictions
or limitations that the Committee, in its discretion, deems appropriate. Any
fraction of a Share required to satisfy such obligation shall be disregarded and
the amount due shall instead be paid in cash by the Grantee.

         The Company shall have the right to take such other action as may be
necessary or appropriate to satisfy any such tax withholding obligations.

         SECTION 10. RESTRICTIONS ON EXERCISE. The Option may not be exercised
if the issuance of such Option Shares or the exercise thereof (including but not
limited to the method of payment of the consideration for such Shares) would
constitute a violation of any applicable federal or state securities or other
laws or regulations, any rules or regulations of any stock exchange on which the
Common Stock may be listed or Company policies.

         SECTION 11. GENERAL.

                  (a) NOTICES. All notices under this Agreement shall be mailed
or delivered by hand to the parties at their respective addresses set forth
beneath their signatures below or at such other address as may be designated in
writing by either of the parties to one another. Notices shall be effective upon
receipt.

                  (b) AMENDMENT AND TERMINATION. No amendment, modification or
termination of the Option or this Agreement shall be made at any time without
the written consent of Grantee and Company.


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                  (c) SEVERABILITY. In the event that any provision of this
Agreement shall be held illegal, invalid, or unenforceable for any reason, such
provision shall be fully severable, but shall not affect the remaining
provisions of the Agreement, and the Agreement shall be construed and enforced
as if the illegal, invalid, or unenforceable provision had not been included
herein.

                  (d) SUPERSEDES PRIOR AGREEMENTS. This Agreement shall
supersede and replace all prior agreements and understandings, oral or written,
between the Company, GXT, or any other person and the Grantee regarding the
grant of the Options covered hereby.

                  (e) GOVERNING LAW. The Option shall be construed in accordance
with the laws of the State of Texas without regard to its conflict of law
provisions, to the extent federal law does not supersede and preempt Texas law.

                  (f) COMMUNITY PROPERTY. Each spouse individually is bound by,
and such spouse's interest, if any, in any Shares is subject to, the terms of
this Agreement. Nothing in this Agreement shall create a community property
interest where none otherwise exists.


                            [Signature page follows.]



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         IN WITNESS WHEREOF, this Agreement is executed and entered into
effective on the day and year first above written.

                                                    INPUT/OUTPUT, INC.

                                                    12300 Parc Crest Drive
                                                    Stafford, Texas 77477

                                                    By:
                                                          ----------------------
                                                    Name:
                                                          ----------------------
                                                    Title:
                                                          ----------------------



                                                    ----------------------------

                                                    -------------------, Grantee

                                                    ----------------------------

                                                    ----------------------------

                                                    ----------------------------
                                                             [address]




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