<PAGE>

                                                                     EXHIBIT 4.3

                                    ANNEX A

                           [FORM OF FACE OF SECURITY]

FOR UNITED STATES FEDERAL INCOME TAX PURPOSES, THIS SECURITY BEARS ORIGINAL
ISSUE DISCOUNT.  INFORMATION INCLUDING THE ISSUE PRICE, AMOUNT OF ORIGINAL ISSUE
DISCOUNT, THE ISSUE DATE, AND THE YIELD TO MATURITY WILL BE MADE AVAILABLE TO
HOLDERS UPON REQUEST TO THE CHIEF FINANCIAL OFFICER OF THE COMPANY, AT (713)
513-3300.

                      [FORM OF LEGEND FOR GLOBAL SECURITY]

UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO THE COMPANY OR ITS
AGENT FOR REGISTRATION OF TRANSFERS, EXCHANGE, OR PAYMENT, AND ANY CERTIFICATE
ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME AS IS
REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT IS MADE TO
CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED
REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE, OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED OWNER
HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

TRANSFERS OF THIS GLOBAL SECURITY SHALL BE LIMITED TO TRANSFER IN WHOLE, BUT NOT
IN PART, TO NOMINEES OF DTC OR TO A SUCCESSOR THEREOF OR SUCH SUCCESSOR'S
NOMINEE AND TRANSFERS MADE IN ACCORDANCE WITH THE RESTRICTIONS SET FORTH IN THE
INDENTURE REFERRED TO ON THE REVERSE HEREOF.
<PAGE>

                           COOPER CAMERON CORPORATION

               ZERO COUPON CONVERTIBLE SENIOR DEBENTURE DUE 2021

No.

Issue Date: May 16, 2001                      Original Issue Discount: $220.59
Issue Price: $779.41                          (for each $1,000 Principal Amount)
(for each $1,000 Principal Amount)

                                                              CUSIP:  216640 AA0

     Cooper Cameron Corporation, a Delaware corporation, promises to pay to
______________________ or registered assigns, on May 16, 2021 the Principal
Amount of __________________________________ Dollars ($________________) [or
such greater or lesser Principal Amount as may be shown on Schedule A
hereto].(1)

     This Security shall not bear interest except as specified on the other side
of this Security.  Original Issue Discount will accrue as specified on the other
side of this Security.  This Security is convertible as specified on the other
side of this Security.

     Additional provisions of this Security are set forth on the other side of
this Security.

     IN WITNESS WHEREOF, Cooper Cameron Corporation has caused this instrument
to be duly executed.

                              COOPER CAMERON CORPORATION


                              By:___________________________
                                  Name:
                                  Title:
                                  Dated:

                    TRUSTEE'S CERTIFICATE OF AUTHENTICATION

     Bank One Trust Company, National Association, as successor to The First
National Bank of Chicago, as Trustee, certifies that this is one of the
Securities referred to in the within-mentioned Indenture.


By  _______________________
    Authorized Signatory



---------------------
(1) For inclusion in the global Security only.

                                       2
<PAGE>

                       [FORM OF REVERSE SIDE OF SECURITY]

                           COOPER CAMERON CORPORATION

               ZERO COUPON CONVERTIBLE SENIOR DEBENTURE DUE 2021

     This Security is one of a duly authorized issue of senior securities of the
Company issued and to be issued in one or more series under an Indenture, dated
as of May 8, 1998, as supplemented by the Supplemental Indenture thereto dated
as of May 16, 2001 relating to the Securities (as so supplemented, herein called
the "Indenture"), between the Company and Bank One Trust Company, National
Association, as successor to The First National Bank of Chicago, as Trustee
(herein called the "Trustee," which term includes any successor trustee under
the Indenture), to which Indenture and all indentures supplemental thereto
reference is hereby made for a statement of the respective rights, limitations
of rights, duties and immunities thereunder of the Company, the Trustee and the
Holders of the Securities and of the terms upon which the Securities are, and
are to be, authenticated and delivered. This Security is one of the series
designated on the face hereof, limited in aggregate principal amount to
$320,756,000.  As used herein, the term "Securities" means securities of the
series designated on the face hereof except that, where the context requires
that such term be construed as including another series of securities (e.g.,
where phases such as "Securities of each series" or "Securities of any series"
or similar phases are used), the term "Securities" means securities of any
series issued or to be issued under the Indenture.

1.   Interest

     This Security shall not bear interest except as specified in this paragraph
or in paragraph 10 hereof.  If the Principal Amount hereof or any portion of
such Principal Amount is not paid when due (whether upon acceleration pursuant
to Section 502 of the Indenture, upon the date set for payment of the Redemption
Price pursuant to paragraph 5 hereof, upon the date set for payment of a
Purchase Price or Fundamental Change Purchase Price pursuant to paragraph 6
hereof or upon the Stated Maturity of this Security), then in each such case the
overdue amount shall bear interest at the rate of 1.25% per annum, compounded
semiannually (to the extent that the payment of such interest shall be legally
enforceable), which interest shall accrue from the date such overdue amount was
due to the date payment of such amount, including interest thereon, has been
made or duly provided for.  All such interest shall be payable on demand.  The
accrual of such interest on overdue amounts shall be in lieu of, and not in
addition to, the continued accrual of Original Issue Discount.

     The Original Issue Discount (the difference between the Issue Price and the
Principal Amount of the Security) in the period during which a Security remains
outstanding, shall accrue at 1.25% per annum, on a semiannual bond equivalent
basis using a 360-day year consisting of twelve 30-day months, commencing on the
Issue Date of this Security.  Original Issue Discount shall cease to accrue on
the earlier of (a) the date on which the Principal Amount hereof or any portion
of such Principal Amount becomes due and payable and (b) any Redemption Date,
Conversion Date, Fundamental Change Purchase Date, Purchase Date or other date
on which such Original Issue Discount (or, if such Securities have been
converted to Semiannual Coupon Debentures following the occurrence of a Tax
Event, interest on such debentures) shall cease to accrue in accordance with
Section 1105 of the Indenture.

                                       3
<PAGE>

2.   Method Of Payment

     Holders must surrender Securities to the Paying Agent to collect all
payments in respect of the Securities.  The Company will pay cash amounts in
money of the United States that at the time of payment is legal tender for
payment of public and private debts.  However, the Company may make such cash
payments by check payable in such money or by wire transfer in immediately
available funds.

3.   Paying Agent, Conversion Agent And Registrar

     Initially, Bank One Trust Company, National Association, as successor to
The First National Bank of Chicago (the "Trustee"), will act as Paying Agent,
Conversion Agent and Registrar.  The Company may appoint and change any Paying
Agent, Conversion Agent, Registrar or co-registrar without notice, other than
notice to the Trustee.  The company or any of its Subsidiaries or any of their
Affiliates may act as Paying Agent, Conversion Agent, Registrar or co-registrar.

4.   Indenture

     The Company issued the Securities under an Indenture dated as of May 8,
1998, between the Company and the Trustee (as supplemented by the Supplemental
Indenture, the "Indenture") and a Supplemental Indenture dated as of May 16,
2001 between the Company and the Trustee relating to the Securities (the
"Supplemental Indenture").  Capitalized terms used herein and not defined herein
have the meanings ascribed thereto in the Indenture.  The Securities are subject
to all such terms, and Holders are referred to the Indenture for a statement of
those terms.

     The Securities are general unsecured obligations of the Company limited to
$320,756,000 aggregate Principal Amount (subject to Section 102 of the
Supplemental Indenture).  The Indenture does not limit other indebtedness of the
Company, whether secured or unsecured.

5.   Optional Redemption

     There shall be no sinking fund for the retirement of the Securities.  The
Securities are redeemable as a whole, or from time to time in part, at any time
at the option of the Company at the Redemption Prices set forth below, provided
that the Securities are not redeemable prior to May 17, 2004.

     If the Company redeems less than all of the outstanding Securities, the
Trustee will select the Securities to be redeemed (i) by lot, (ii) pro rata or
(iii) by another method the Trustee considers fair and appropriate. If the
Trustee selects a portion of a Holder's Securities for partial redemption and
the Holder converts a portion of the same Securities, the converted portion will
be deemed to be from the portion selected for redemption.

     The table below shows Redemption Prices of a Security per $1,000 Principal
Amount on the dates shown below and at Stated Maturity, which prices reflect
accrued Original Issue Discount calculated to each such date.  The Redemption
Price of a Security redeemed between such dates would include an additional
amount reflecting the additional Original Issue Discount accrued since the next
preceding date in the table to the actual Redemption Date.

                                       4
<PAGE>

<TABLE>
<CAPTION>
                                                                                 (2)
                                                                               ACCRUED
                                                                (1)           ORIGINAL
                                                             DEBENTURE          ISSUE            (3)
                                                               ISSUE          DISCOUNT        REDEMPTION
                                                               PRICE          AT 1.25%      PRICE (1) + (2)
                                                             ---------      -----------    ----------------
<S>                                                              <C>              <C>              <C>
May 17, 2004..........................................         $779.41          $ 29.69       $  809.10
May 17, 2005..........................................         $779.41          $ 39.83       $  819.24
May 17, 2006..........................................         $779.41          $ 50.11       $  829.52
May 17, 2007..........................................         $779.41          $ 60.51       $  839.92
May 17, 2008..........................................         $779.41          $ 71.04       $  850.45
May 17, 2009..........................................         $779.41          $ 81.70       $  861.11
May 17, 2010..........................................         $779.41          $ 92.50       $  871.91
May 17, 2011..........................................         $779.41          $103.43       $  882.84
May 17, 2012..........................................         $779.41          $114.50       $  893.91
May 17, 2013..........................................         $779.41          $125.71       $  905.12
May 17, 2014..........................................         $779.41          $137.06       $  916.47
May 17, 2015..........................................         $779.41          $148.55       $  927.96
May 17, 2016..........................................         $779.41          $160.19       $  939.60
May 17, 2017..........................................         $779.41          $171.97       $  951.38
May 17, 2018..........................................         $779.41          $183.90       $  963.31
May 17, 2019..........................................         $779.41          $195.98       $  975.39
May 17, 2020..........................................         $779.41          $208.21       $  987.62
At Stated Maturity (May 17, 2021).....................         $779.41          $220.59       $1,000.00
</TABLE>

     If converted to a Semiannual Coupon Debenture following the occurrence of a
Tax Event, this Security will be redeemable at the Restated Principal Amount
plus interest accrued and unpaid from, and including, the date of such
conversion to, but excluding, the Redemption Date.

6.   Repurchase at the Option of the Holder; Repurchase at the Option of the
     Holder upon a Fundamental Change

     (a) Subject to the terms and conditions of the Indenture, the Company shall
become obligated to repurchase, at the option of the Holder, the Securities held
by such Holder on the following Purchase Dates and at the following Purchase
Prices per $1,000 Principal Amount upon delivery of a Purchase Notice containing
the information set forth in the Indenture, at any time during the period from
the opening of business on the date that is 20 Business Days prior to such
Purchase Date until the close of business on such Purchase Date and upon
delivery of the Securities to the Paying Agent by the Holder as set forth in
Section 1108(a)(1) of the Indenture.  Such Purchase Prices may be paid, at the
option of the Company, in cash or by the issuance and delivery of shares of
Common Stock of the Company, or in any combination thereof, as set forth in the
Indenture.

                PURCHASE DATE           PURCHASE PRICE
                -------------           --------------
                May 17, 2004               $809.10
                May 17, 2009               $861.11
                May 17, 2014               $916.47

                                       5
<PAGE>

     Securities in denominations larger than $1,000 of Principal Amount may be
repurchased in part, but only in integral multiples of $1,000 of Principal
Amount.

     (b) If prior to a Purchase Date this Security has been converted to a
Semiannual Coupon Debenture following the occurrence of a Tax Event, the
Purchase Price will be equal to the Restated Principal Amount plus accrued and
unpaid interest from, and including, the date of conversion to, but excluding,
the Purchase Date.

     (c) At the option of the Holder and subject to the terms and conditions of
the Indenture, the Company shall become obligated to repurchase the Securities
held by such Holder and delivered to the Company or its designated agent on the
date that is 30 days after the date of the Company's notice of a Fundamental
Change occurring on or prior to May 16, 2021 (or if such date is not a Business
Day, the next succeeding Business Day) for a Fundamental Change Purchase Price
equal to the Issue Price plus accrued Original Issue Discount to the Fundamental
Change Purchase Date which Fundamental Change Purchase Price shall be paid in
cash.  Securities in denominations larger than $1,000 of Principal Amount may be
repurchased in part in connection with a Fundamental Change, but only in
integral multiples of $1,000 of Principal Amount.  If, prior to a Fundamental
Change Purchase Date, this Security has been converted to a Semiannual Coupon
Debenture following the occurrence of a Tax Event, the Purchase Price will be
equal to the Restated Principal Amount plus accrued and unpaid interest from,
and including, the date of conversion to, but excluding, the Fundamental Change
Purchase Date.

     (d) Holders have the right to withdraw any Purchase Notice or Fundamental
Change Purchase Notice, as the case may be, by delivering to the Paying Agent a
written notice of withdrawal in accordance with the provisions of the Indenture.

     (e) If cash (and/or securities if permitted under the Indenture) sufficient
to pay a Purchase Price or Fundamental Change Purchase Price, as the case may
be, of all Securities or portions thereof to be repurchased as of the Purchase
Date or the Fundamental Change Purchase Date, as the case may be, is deposited
with the Paying Agent on the Business Day following the Purchase Date or the
Fundamental Change Purchase Date, as the case may be, Original Issue Discount
(or interest upon conversion to a Semiannual Coupon Debenture following the
occurrence of a Tax Event) ceases to accrue on such Securities (or portions
thereof) on and after such date, and the Holder thereof shall have no other
rights as such (other than the right to receive the Purchase Price or
Fundamental Change Purchase Price, as the case may be, upon surrender of such
Security).

7.   Notice of Redemption; Procedures

     Notice of redemption at the option of the Company will be mailed to each
Holder of Securities to be redeemed at the Holder's registered address at least
30 days but not more than 60 days before the Redemption Date.  If money
sufficient to pay the Redemption Price of all Securities (or portions thereof)
to be redeemed on the Redemption Date is deposited with the Paying Agent prior
to or on the Redemption Date, on and after such date Original Issue Discount (or
interest upon conversion to a Semiannual Coupon Debenture following the
occurrence of a Tax Event) ceases to accrue on such Securities or portions
thereof.  Securities in denominations larger than $1,000 of Principal Amount may
be redeemed in part but only in multiples of $1,000 of Principal Amount.

                                       6
<PAGE>

8.   Ranking

     The Securities rank equally in contractual right of payment with all of the
other existing and future unsubordinated and unsecured indebtedness of the
Company.

9.   Conversion

     Subject to the next two succeeding sentences, a Holder of a Security may
convert this Security for Common Stock of the Company at any time until 5 p.m.,
New York City time on the Stated Maturity.  If this Security is called for
redemption, the Holder may convert it at any time before the close of the third
Business Day prior to the Redemption Date.  A Security in respect of which a
Holder has delivered a notice of exercise of the option to require the Company
to repurchase such Security or to repurchase such Security in the event of a
Fundamental Change may be converted only if the notice of exercise is withdrawn
in accordance with the terms of the Indenture.

     The initial Conversion Rate is 8.1961 shares of Common Stock per $1,000
Principal Amount, subject to adjustment in certain events described in the
Indenture.  The Company will deliver cash or a check in lieu of any fractional
share of Common Stock.

     In the event the Company exercises its option pursuant to Section 1406 of
the Indenture to have interest in lieu of Original Issue Discount accrue on the
Security following a Tax Event, any Security or portion thereof surrendered for
conversion after the first Interest Payment Date with respect to the Securities
must be accompanied by a payment, in funds acceptable to the Company, equal to
the sum of all cash interest paid on the Security or portion thereof being
converted, plus (in the case of the Security or portion thereof being
surrendered for conversion during the period from the close of business on the
Record Date next preceding the next Interest Payment Date to the opening of
business on the next Interest Payment Date) the amount of interest otherwise
payable on such Interest Payment Date on the amount of principal being
converted.

     Except where Securities surrendered for conversion must be accompanied by
payment as described above, no interest on converted Securities will be payable
by the Company on any Interest Payment Date subsequent to the date of
conversion.

     To convert this Security a Holder must (1) complete and manually sign the
conversion notice on the back of this Security (or complete and manually sign a
facsimile of such notice) and deliver such notice to the Conversion Agent, (2)
surrender this Security to the Conversion Agent, (3) furnish appropriate
endorsements and transfer documents if required by the Conversion Agent, the
Company or the Trustee and (4) pay any transfer or similar tax, if required.

     A Holder may convert a portion of this Security if the Principal Amount of
such portion is $1,000 or an integral multiple of $1,000.  No payment or
adjustment will be made for dividends on the Common Stock except as provided in
the Indenture.  On conversion of this Security, that portion of accrued Original
Issue Discount attributable to the period from the Issue Date to the Conversion
Date with respect to the converted portion of this Security shall not be
canceled, extinguished or forfeited, but rather shall be deemed to be paid in
full to the Holder thereof through the delivery of the Common Stock (together
with any cash payment in lieu of

                                       7
<PAGE>

fractional shares) in exchange for the portion of this Security being converted
pursuant to the terms hereof.

10.  Tax Event

     (a) From and after the date (the "Tax Event Date") of the occurrence of a
Tax Event, at the option of the Company, interest in lieu of future Original
Issue Discount shall accrue at 1.25% per annum on a principal amount per
Security (the "Restated Principal Amount") equal to the Issue Price plus
Original Issue Discount accrued to the date immediately prior to the later of
the Tax Event Date or the date the Company makes its election and shall be
payable semiannually on May 15 and November 15 of each year (each an "Interest
Payment Date") to Holders of record at the close of business on May 1 or
November 1 (each a "Regular Record Date") immediately preceding such Interest
Payment Date.  Interest will be computed on the basis of a 360-day year
comprised of twelve 30-day months and will accrue from the most recent date to
which interest has been paid or, if no interest has been paid, from the Tax
Event Date.

     (b) Interest on any Security that is payable, and is punctually paid or
duly provided for, on any Interest Payment Date shall be paid to the Person in
whose name that Security is registered at the close of business on the Regular
Record Date for such interest at the office or agency of the Company maintained
for such purpose.

     (c) Except as otherwise specified with respect to the Securities, any
interest on any Security that is payable, but is not punctually paid or duly
provided for, on any Interest Payment Date (herein called "Defaulted Interest")
shall forthwith cease to be payable to the Holder thereof on the relevant
Regular Record Date by virtue of having been such Holder, and such Defaulted
Interest may be paid by the Company as provided for in Section 1406(d) of the
Indenture.

11.  Conversion Arrangement on Call for Redemption

     Any Securities called for redemption, unless surrendered for conversion
before the close of business on the last Trading Day prior to the Redemption
Date, may be deemed to be purchased from the Holders of such Securities at an
amount not less than the Redemption Price, by one or more investment bankers or
other purchasers who may agree with the Company to purchase such Securities from
the Holders, to convert them for Common Stock and to make payment for such
Securities to the Trustee in trust for such Holders.

12.  Denominations; Transfer; Exchange

     The Securities are in registered form, without coupons, in denominations of
$1,000 of Principal Amount and integral multiples of $1,000.  A Holder may
transfer or convert Securities in accordance with the Indenture.  The Registrar
may require a Holder, among other things, to furnish appropriate endorsements
and transfer documents and to pay any taxes and fees required by law or
permitted by the Indenture.  The Registrar need not transfer or exchange any
Securities selected for redemption (except, in the case of a Security to be
redeemed in part, the portion of the Security not to be redeemed) or any
Securities in respect of which a Purchase Notice or Fundamental Change Purchase
Notice has been given and not withdrawn (except, in the case of a Security to be
purchased in part, the portion of the Security not to be purchased) or any
Securities for a period of 15 days before the mailing of notice of Securities to
be redeemed.

                                       8
<PAGE>

13.  Persons Deemed Owners

     The registered holder of this Security may be treated as the owner of this
Security for all purposes.

14.  Unclaimed Money Or Securities

     The Trustee and the Paying Agent shall return to the Company upon written
request any money or securities held by them for the payment of any amount with
respect to the Securities that remains unclaimed for two years, provided,
however, that the Trustee or such Paying Agent, before being required to make
any such return, shall in the event that the Securities are no longer held in
global form, at the expense of the Company cause to be published once in a
newspaper of general circulation in The City of New York or mail to each such
Holder notice that such money or securities remains unclaimed and that, after a
date specified therein, which shall not be less than 30 days from the date of
such publication or mailing, any unclaimed money or securities then remaining
will be returned to the Company.  After return to the Company, Holders entitled
to the money or securities must look to the Company for payment as general
creditors unless an applicable abandoned property law designates another Person.

15.  Amendment; Waiver

     Subject to certain exceptions set forth in the Indenture, (i) the Indenture
or the Securities may be amended with the written consent of the Holders of at
least a majority in aggregate Principal Amount of the Securities at the time
outstanding (or, in certain cases, of all debt securities under the Indenture)
and (ii) certain Defaults and Events of Defaults may be waived with the written
consent of the Holders of a majority in aggregate Principal Amount of the
Securities at the time outstanding (or, in certain cases, of all debt securities
under the Indenture).  Subject to certain exceptions set forth in the Indenture,
without the consent of any Holder, the Company and the Trustee may amend the
Indenture or the Securities to cure any ambiguity, defect or inconsistency, to
provide for the assumption of the Company's obligations to the Holders of the
Securities in case of a merger or consolidation or sale of all or substantially
all of the Company's assets, to provide for uncertificated Securities in
addition to or in place of certificated Securities, to make any change that does
not adversely affect the rights of any Holder or to comply with any requirement
of the Commission in connection with the qualification of the Indenture under
the Trust Indenture Act.

16.  Limitation on Suits

     Subject to the right of the Holder of any Securities of this series to
institute proceedings to enforce the Holder's right to receive payment of the
Issue Price plus accrued Original Issue Discount, or the Restated Principal
Amount plus accrued and unpaid interest (subject to Section 307 of the
Indenture) with respect to such Security on the Stated Maturity or Maturities
expressed in such Security (or in the case of redemption, to receive the
Redemption Price on the Redemption Date, in the case of a repurchase, to receive
the Purchase Price on the Purchase Date, or in the case of a Fundamental Change,
to receive the Fundamental Change Purchase Price on the Fundamental Change
Purchase Date) and to institute suit for the enforcement of any such payment on
or after such respective dates, and to receive shares on conversion, no Holder
of the Securities of this series shall have any right to institute any
proceeding, judicial or otherwise,

                                       9
<PAGE>

with respect to the Indenture, or for the appointment of a receiver or trustee,
or for any other remedy hereunder, unless

     (1) an Event of Default with respect to the Securities of this series shall
have occurred and be continuing and such Holder has previously given written
notice to the Trustee of such continuing Event of Default;

     (2) the Holders of not less than 25% in principal amount of the Outstanding
Securities of this series shall have made written request to the Trustee to
institute proceedings in respect of such Event of Default in its own name as
Trustee hereunder;

     (3) such Holder or Holders have offered to the Trustee reasonable indemnity
against the costs, expenses and liabilities to be incurred in compliance with
such request;

     (4) the Trustee for 60 days after its receipt of such notice, request and
offer of indemnity has failed to institute any such proceeding; and

     (5) no direction inconsistent with such written request has been given to
the Trustee during such 60-day period by the Holders of a majority in principal
amount of the Outstanding Securities of this series.

17.  Defaults And Remedies

     If an Event of Default with respect to Securities of this series shall
occur and be continuing, the Issue Price plus accrued Original Issue Discount,
or the Restated Principal Amount plus accrued and unpaid interest from the date
of conversion to the acceleration date of the Securities of this series may be
declared due and payable in the manner and with the effect provided in the
Indenture.

18.  Trustee Dealings With The Company

     The Trustee under the Indenture, in its individual or any other capacity,
may become the owner or pledgee of Securities and may otherwise deal with and
collect obligations owed to it by the Company or its Affiliates and may
otherwise deal with the Company or its Affiliates with the same rights it would
have if it were not Trustee.

19.  No Recourse Against Others

     A director, officer, employee or stockholder, as such, of the Company shall
not have any liability for any obligations of the Company under the Securities
or the Indenture or for any claim based on, in respect of or by reason of such
obligations or their creation.  By accepting a Security, each Holder waives and
releases all such liability.  The waiver and release are part of the
consideration for the issue of the Securities.

20.  Authentication

     This Security shall not be valid until an authorized signatory of the
Trustee manually signs the Trustee's Certificate of Authentication on the other
side of this Security.

                                       10
<PAGE>

21.  Abbreviations

     Customary abbreviations may be used in the name of a Holder or an assignee,
such as TEN COM (=tenants in common), TENANT (=tenants by the entireties), JT
TEN (=joint tenants with right of survivorship and not as tenants in common),
CUST (=custodian), and U/G/M/A (=Uniform Gift to Minors Act).

22.  Governing Law

     THE LAWS OF THE STATE OF NEW YORK SHALL GOVERN THE INDENTURE AND THIS
SECURITY.

23.  Indenture To Control

     In case of any conflict between the provisions of this Security and the
Indenture, the provisions of the Indenture shall control.

     The Company will furnish to any Holder upon written request and without
charge a copy of the Indenture.  Requests may be made to:

               Cooper Cameron Corporation
               515 Post Oak Blvd.
               Suite 1200
               Houston, Texas  77027
               713.513.3300
               Attention:  Corporate Secretary

                                       11
<PAGE>

                               CONVERSION NOTICE

To:   Cooper Cameron Corporation

      The undersigned registered holder of this Security hereby irrevocably
exercises the option to convert this Security, or portion hereof (which is
$1,000 Principal Amount (as defined in the Indenture to which this Security is
subject) or an integral multiple thereof) below designated, for shares of Common
Stock of Cooper Cameron Corporation in accordance with the terms of the
Indenture referred to in this Security, and directs that the shares issuable and
deliverable upon such conversion, together with any check in payment for
fractional shares and any Securities representing any unconverted Principal
Amount hereof, be issued and delivered to the registered holder hereof unless a
different name has been indicated below.  If shares or any portion of this
Security not converted are to be issued in the name of a Person other than the
undersigned, the undersigned will pay all transfer taxes payable with respect
thereto.

Dated:                                  _________________________________

                                        _________________________________
                                                    Signature(s)

Fill in for registration of shares
if to be delivered, and Securities
if to be issued other than to and in
the name of the registered holder:


__________________________________
(Name)



__________________________________
(Street Address)



__________________________________
(City, state and zip code)

Please print name and address

                              Principal Amount to be converted
                              (if less than all):
                              $_________,000
                              Social Security or Other Taxpayer
                              Identification Number:  ____________

                                       12
<PAGE>

              OPTION TO ELECT REPURCHASE UPON A FUNDAMENTAL CHANGE

To:   Cooper Cameron Corporation

      The undersigned registered holder of this Security hereby acknowledges
receipt of a notice from Cooper Cameron Corporation (the "Company") as to the
occurrence of a Fundamental Change with respect to the Company and requests and
instructs the Company to repurchase this Security, or the portion hereof (which
is $1,000 Principal Amount (as defined in the Indenture to which this Security
is subject) or an integral multiple thereof) below designated, in accordance
with the terms of the Indenture referred to in this Security.

Dated:______________________


                                     __________________________________
                                               Signature(s)

                                     Principal Amount to be repurchased
                                     (if less than all):
                                     $________,000
                                     Social Security or Other Taxpayer
                                     Identification Number:  ___________

                                       13
<PAGE>

                                TRANSFER NOTICE

This Transfer Notice relates to $__________ Principal Amount (as defined in the
Indenture to which the referenced Securities are subject) of the Zero Coupon
Convertible Senior Debentures due 2021 of Cooper Cameron Corporation, a Delaware
corporation, held by ____________ (the "Transferor").

                (I) or (we) assign and transfer this Security to


________________________________________________________________________________
             (Print or type assignee's name, address and zip code)


________________________________________________________________________________


________________________________________________________________________________
              (Insert assignee's social security or tax I.D. no.)

and irrevocably appoint _______________________________ agent to transfer this
Security on the books of the Company.  The agent may substitute another to act
for him.

Your Signature:_________________________________________________________________
     (Sign exactly as your name appears on the other side of this Security)

     Date:______________________________________________________________________

                                       14
<PAGE>

                                   SCHEDULE A

                 Changes to Principal Amount of Global Security

<TABLE>
<CAPTION>

                           PRINCIPAL AMOUNT OF SECURITIES
                           BY WHICH THIS GLOBAL SECURITY
                           IS TO BE REDUCED OR INCREASED,
                                   AND REASON FOR             REMAINING PRINCIPAL AMOUNT      NOTATION
          DATE                 REDUCTION OR INCREASE           OF THIS GLOBAL SECURITY        MADE BY
----------------------   ----------------------------------   ---------------------------    ----------
<S>                                  <C>                                 <C>                 <C>
</TABLE>

                                       15