<PAGE>
                                                                    EXHIBIT 4.04



                          FORM OF SENIOR DEBT SECURITY
[Face of Security]
                                LEXAR MEDIA, INC.

         [If applicable, insert -- FOR PURPOSES OF THE ORIGINAL ISSUE DISCOUNT
PROVISIONS OF THE INTERNAL REVENUE CODE OF 1986, THE ISSUE PRICE OF THIS
SECURITY IS ___% OF ITS PRINCIPAL AMOUNT AT STATED MATURITY SET FORTH BELOW (ITS
"PRINCIPAL AMOUNT"), THE AMOUNT OF ORIGINAL ISSUE DISCOUNT IS ___% OF ITS
PRINCIPAL AMOUNT, THE YIELD TO MATURITY IS ___% AND THE ISSUE DATE IS
____________]

         [IF THE SECURITY IS A GLOBAL SECURITY, INSERT -- THIS NOTE IS A GLOBAL
SECURITY. IT IS EXCHANGEABLE FOR NOTES REGISTERED IN THE NAME OF A PERSON OTHER
THAN THE DEPOSITARY (AS HEREINAFTER DEFINED) OR ITS NOMINEE ONLY IN THE LIMITED
CIRCUMSTANCES HEREINAFTER DESCRIBED AND MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE
BY THE DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE
DEPOSITARY TO THE DEPOSITARY OR ANOTHER NOMINEE OF THE DEPOSITARY OR BY THE
DEPOSITARY OR A NOMINEE OF THE DEPOSITARY TO A SUCCESSOR OF THE DEPOSITARY OR A
NOMINEE OF SUCH SUCCESSOR DEPOSITARY.]

         [Unless this Security is presented by an authorized representative of
The Depositary Trust Company (55 Water Street, New York, New York) to the issuer
or its agent for registration of transfer, exchange or payment and any
certificate issued is registered in the name of Cede & co. or such other name as
requested by an authorized representative of The Depository Trust Company and
any payment is made to Cede & Co., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR
VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL since the registered owner
hereof, Cede & Co., has an interest herein.]

No. ________                                                          $________
                                                                       CUSIP No.

         Lexar Media, Inc., a Delaware Corporation (herein called the "Company",
which term includes any successor corporation under the Indenture referred to on
the reverse hereof), for value received, hereby promises to pay to [If the
Security is to be in registered form, insert--, or registered assigns] [If the
Security is to be in coupon form, insert--the bearer hereof upon surrender], the
principal sum of ________ Dollars on ------------- [if Security is to bear
interest prior to maturity, insert --, and to pay interest thereon from
------------------- or from the most recent Interest Payment Date to which
interest has been paid or duly provided for, semi-annually on ------------ and
------------- in each year, commencing ----------------, at the rate of ___% per
annum, until the principal hereof is paid or made available for payment [if
applicable, insert ---, provided that any principal and premium, and any such
installment of interest, which is overdue shall bear interest at the rate of
___% per annum (to the extent that the payment of such interest shall be legally
enforceable), from the dates such amounts are due until they are paid or made
available for payment, and such interest shall be payable on demand]. The
interest so payable, and punctually paid or duly provided for, on any Interest
Payment Date will, as provided in such Indenture, be paid to the Person in whose
name this Security (or one or more Predecessor Securities) is registered at the
close of business on the Record Date for such interest, which shall


<PAGE>


be the ------------ or ---------- (whether or not a Business Day), as the case
may be, next preceding such Interest Payment Date. Any such interest not so
punctually paid or duly provided for will forthwith cease to be payable to the
Holder on such Record Date and may either be paid to the Person this Security
(or one or more Predecessor Securities) is registered at the close of business
on a Special Record Date for the payment of such Defaulted Interest to be fixed
by the Trustee, notice whereof shall be given to Holders of Securities of this
series not less than 10 days prior to such Special Record Date, or be paid at
any time in any other lawful manner not inconsistent with the requirements of
any securities exchange on which the Securities of this series may be listed,
and upon such notice as may be required by such exchange, all as more fully
provided in said Indenture. [If the Security is not to bear interest prior to
maturity, insert --- The principal of this Security shall not bear interest
except in the case of a default in payment of principal upon acceleration, upon
redemption or at Stated Maturity and in such case the overdue principal and any
overdue premium shall bear interest at the rate of ___% per annum (to the extent
that the payment of such interest shall be legally enforceable), from the dates
such amounts are due until they are paid or made available for payment. Interest
on any overdue principal or premium shall be payable on demand. [Any such
interest on overdue principal or premium which is not paid on demand shall bear
interest at the rate of ___% per annum (to the extent that the payment of such
interest on interest shall be legally enforceable), from the date of such demand
until the amount so demanded is paid or made available for payment. Interest on
any overdue interest shall be payable on demand.]].

         Payment of the principal of (and premium, if any, on) and [any such]
interest on this Security will be made at the office or agency of the Company
maintained for that purpose in _______, in such coin or currency of [the United
States of America] as at the time of payment is legal tender for payment of
public and private debts [; provided, however, that at the option of the Company
payment of interest may be made by check mailed to the address of the Person
entitled thereto as such address shall appear in the Register].

         Reference is hereby made to the further provisions of this Security set
forth on the reverse hereof, which further provisions shall for all purposes
have the same effect as if set forth at this place.

         Unless the certificate of authentication hereon has been manually
executed by or on behalf of the Trustee under the Indenture referred to on the
reverse hereof, this Security shall not be entitled to any benefit under the
Indenture or be valid or obligatory for any purpose.

         IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed under its corporate seal.

Dated:                                               Lexar Media, Inc.


                                                     By: _______________________
                                                                [Title]
Attest and Countersign:


--------------------------
      Secretary




                                       2
<PAGE>


[Reverse of Security.]

                               LEXAR MEDIA, INC.

         This Security is one of a duly authorized issue of securities of the
Company (herein called the "Securities"), issued and to be issued in one or more
series under an Indenture dated as of ____________ (herein called the
"Indenture," which term shall have the meaning assigned to it in such
instrument), between the Company and _______________, 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 or 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 $_______].

         [If the Security is to be subordinated, insert--The indebtedness
evidenced by this Security is, to the extent and in the manner set forth in the
Indenture, expressly subordinated and subject in right of payment to the prior
payment in full of all Senior Indebtedness (as defined in the Indenture) of the
Company. This Security is issued subject to such provisions of the Indenture,
and each Holder of this Security, by accepting the same, agrees to and shall be
bound by such provisions and authorizes and directs the Trustee on the Holder's
behalf to take such action as may be necessary or appropriate to acknowledge or
effectuate such subordination as provided in the Indenture and appoints the
Trustee such Holder's attorney-in-fact for any and all such purposes.]

         [If the Security is to be subject to redemption only at the option of
the Company or any sinking fund redemption will be at the same prices,
insert--The Securities of this series are subject to redemption upon not less
than 30 days' notice provided in the manner set forth in the Indenture, [(1) on
_________ in any year commencing with the year __________ and ending with the
year __________ through operation of the sinking fund for this series at the
Redemption Price equal to 100% of the principal amount, and (2)] at any time [on
or after ____________, ________], as a whole or in part, at the election of the
principal the following Redemption Prices (expressed as percentages of the
principal amount): If redeemed [on or before ___________, ___%, and if redeemed]
during the 12-month period beginning _________ of the years indicated,


Year             Redemption Price                 Year          Redemption Price
----             ----------------                 ----          ----------------



and thereafter at a Redemption Price equal to ___% of the principal amount
together in the case of any such redemption [(whether through operation of the
sinking fund or otherwise)] with accrued interest to the Redemption Date, but
interest installments whose Stated Maturity is on or prior to such Redemption
Date will be payable to the Holders of such Securities of record at the


                                       1
<PAGE>


close of business on the relevant record dates referred to on the face hereof,
all as provided in the Indenture.]

         [If the Security is to be subject to redemption at the option of the
Company and pursuant to a sinking fund at different prices, insert--The
Securities of this series are subject to redemption upon not less than 30 days'
notice by mail, (1) on _______ in any year commencing with the year _______ and
ending with the year _______ through operation of the sinking fund for this
series at the Redemption Prices of redemption through operation of the sinking
fund (expressed as percentages of the principal amount) set forth in the table
below, and (2) at any time [on or after _______], as a whole or in part, at the
election of the Company, at the Redemption Prices for redemption otherwise than
through operation of the sinking fund (expressed as percentages of the principal
amount) set forth in the table below: If redeemed during the 12-month period
beginning in the years indicated,

           Redemption Price for                Redemption Price for Redemption
           Redemption Through Operation        Otherwise Than Through Operation
Year       of the Sinking Fund                 of the Sinking Fund
----       ----------------------------        -------------------------------


and thereafter at a Redemption Price equal to ___% of the principal amount,
together in the case of any such redemption (whether through operation of the
sinking fund or otherwise) with accrued interest to the Redemption Date, but
interest installments whose Stated Maturity is on or prior to such Redemption
Date will be payable to the Holders of such Securities of record at the close of
business on the relevant record dates referred to on the face hereof, all as
provided in the Indenture.]

         [If there is to be a sinking fund, insert--The sinking fund for this
series provides for the redemption on _______ each year beginning with the year
_______ and ending with the year _______ of [not less than] $_______ ("mandatory
sinking fund") and not more than $_______] aggregate principal amount of
Securities of this series. Securities of this series acquired or redeemed by the
Company otherwise than through [mandatory] sinking fund payments may be credited
against subsequent [mandatory] sinking fund payments otherwise required to be
made.]

         [If the Security is to be redeemable in part, insert--In the event of
redemption of this Security in part only, a new Security or Securities of this
series for the unredeemed portion hereof will be issued in the name of the
Holder hereof upon the cancellation hereof.]

         [If the Security is to be subject to repayment at the option of the
Holder, insert--To be repaid at the option of the Holder, the Company must
receive this Security, with the form of "Option to Elect Repayment" hereon duly
completed, at an office or agency of the Company maintained for that purpose in
_______ (or at such other place of which the Company shall from time to time
notify the Holder of this Security) not less than nor more than _______ days
prior to the Repayment Date. The exercise of the repayment option by the Holder
shall be irrevocable.


                                       2
<PAGE>


         [If the Security is not to be subject to redemption at the option of
the Company, insert--The Securities are not redeemable at the option of the
Company prior to Maturity.]

         [If the Security is not to be an Original Issue Discount Security,
insert--If an Event of Default with respect to Securities of this series shall
occur and be continuing, the principal of the Securities of this series may be
declared due and payable in the manner and with the effect provided in the
Indenture.]

         The Indenture permits, with certain exceptions as therein provided, the
amendment thereof and the modification of the rights and obligations of the
Company and the rights of the Holders of the Securities of each series under the
Indenture to be affected at any time by the Company with the consent of the
Holders of not less than 66-2/3% in principal amount of the Securities at the
time Outstanding of each series to be affected. The Indenture also contains
provisions permitting the Holders of specified percentages in principal amount
of the Securities of each series at the time Outstanding, on behalf of the
Holders of all Securities of such series, to waive compliance by the Company
with certain provisions of the Indenture and certain past defaults under the
Indenture and their consequences. Any such consent or waiver by the Holder of
this Security shall be conclusive and binding upon such Holder and upon all
future Holders of this Security and of any Security issued upon the registration
of transfer hereof or in exchange herefor or I lieu hereof, whether or not
notation of such consent of waiver is made upon this Security.

         As provided in and subject to the provisions of the indenture, the
Holder of this Security shall not have the right to institute any proceeding
with respect to the Indenture or for the appointment of a receiver or trustee or
for any other remedy thereunder, unless such Holder shall have previously given
the Trustee written notice of a continuing Event of Default with respect to the
Securities of this series , the Holders of not less than 25% in principal amount
of the Securities of this series at the time Outstanding shall have made written
request to the trustee to institute proceedings in respect of such Event of
Default as Trustee and offered the Trustee reasonable indemnity satisfactory to
it, and the Trustee shall not have received from the Holders of a majority in
principal amount of Securities of this series at the time Outstanding a
direction inconsistent with such request, and shall have failed to institute any
such proceeding, for 60 days after receipt of such notice, request and offer of
indemnity. The foregoing shall not apply to any suit instituted by the Holder of
this Security for the enforcement of any payment of principal hereof or any
premium or interest hereon on or after the respective due dates expressed
herein.

         No reference herein to the Indenture and no provision of this Security
or of the Indenture shall alter or impair the obligation of the Company, which
is absolute and unconditional, to pay the principal of (and premium, if any, on)
and interest on this Security at the times, place and rate, and in the coin or
currency, herein prescribed.

         [If the Security is to be registered form, insert--As provided in the
Indenture and subject to certain limitations therein set forth, the transfer of
this Security is registrable in the Register, upon surrender of this Security
for registration of transfer at the office or agency of the Company in any place
where the principal of (and premium, if any, on) and interest on this Security
are payable, duly endorsed by, or accompanied by a written instrument of
transfer in form satisfactory to the Company and the Registrar duly executed by,
the Holder hereof or his attorney


                                       3
<PAGE>


duly authorized in writing, and, thereupon one or more new Securities of this
series, of authorized denominations and for the same aggregate principal amount,
will be issued to the designated transferee or transferees.]

         [The Securities of this series are issuable only in registered form
[without coupons] in denominations of $_______ [and any integral multiple] [or
increments of $________ in excess] thereof. As provided in the Indenture and
subject to certain limitations therein set forth, Securities of this series are
exchangeable for a like aggregate principal amount of Securities of this series
of a different authorized denomination, as requested by the Holder surrendering
the same.]

         [No service charge shall be made for any such registration of transfer
or exchange, but the Company may require payment of a sum sufficient to cover
any tax or other governmental charge payable in connection therewith.]

         [Prior to due presentment of this Security for registration of
transfer, the Company, the Trustee and any agent of the Company or the Trustee
may treat the Person in whose name this Security is registered as the owner
hereof for all purposes, whether or not this Security be overdue, and neither
the Company, the Trustee nor any such agent shall be affected by notice to the
contrary.]

         [If the Security is a Global Security, insert--"Global Security" and
"Global Securities" means a Security or Securities evidencing all or a part of a
series of Securities, issued to the Depositary (as hereinafter defined) for such
Series or its nominee, and registered in the name of such Depositary or its
nominee. "Depositary" means, with respect to the Securities of any series
issuable or issued in whole or in part in the form of one or more Global
Securities, the person designated as the Depositary by the Company.

         No holder of any beneficial interest in this Security held on its
behalf by a Depositary or a nominee of such Depositary shall have any rights
under the Indenture with respect to such Global Security, and such Depositary or
nominee may be treated by the Company, the Trustee, and any agent of the Company
or the Trustee as the owner of such Global Security for all purposes whatsoever.
Notwithstanding the foregoing, nothing herein shall impair, as between a
Depositary and such holders of beneficial interests, the operation of customary
practices governing the exercise of the rights of the Depositary as Holder of
any Security.

         This Security is exchangeable, in whole but not in part, for Securities
registered in the names of Persons other than the Depositary or its nominee or
in the name of a successor to the Depositary or a nominee of such successor
depositary only if (i) the Depositary notifies the Company that it is unwilling
or unable to continue as Depositary for this Note or if at any time such
Depositary ceases to be a clearing agency registered under the Securities
Exchange Act of 1934, as amended, and, in either case, a successor depositary is
not appointed by the Company within 90 days, (ii) the Company in its discretion
at any time determines not to have all of the Securities of this series
represented by one or more Global Security or Securities and notifies the
Trustee thereof, or (iii) an Event of Default has occurred and is continuing
with respect to the Securities of this series. If this Security is exchangeable
pursuant to the preceding sentence, it shall be exchangeable for Securities
issuable in authorized denominations and registered in such names as the
Depositary holding this Security shall direct. Subject to the foregoing, this
Security


                                       4
<PAGE>


is not exchangeable, except for a Security or Securities of the same aggregate
denominations to be registered in the name of such Depositary or its nominee or
in the name of a successor to the Depositary or a nominee of such successor
depositary.]

         [The Indenture entitles Holders to receive annual reports with respect
to the Trustee's eligibility and qualifications to serve as Trustee by filing
their names and addresses with the Trustee for that purpose within two years
preceding and mailing of any such annual report.]

         No recourse shall be had for the payment of the principal of (and
premium, if any, on) or interest on this Security, or for any claim based
hereon, or otherwise in respect hereof, or based on or in respect of the
Indenture of any indenture supplemental thereto, against any incorporator,
stockholder, officer or director, as such, past, present or future, of the
Company or any successor corporation, whether by virtue of any constitution,
statute or rule of law, or by the enforcement of any assessment or penalty or
otherwise, all such liability being, by the acceptance hereof and as part of the
consideration for the issue hereof, expressly waived and released.

         All terms used in this Security which are defined in the Indenture
shall have the meanings assigned to them in the Indenture.

         This Security, including without limitation the obligation of the
Company contained herein to pay the principal of (and premium, if any, on) and
interest on this Security in accordance with the terms hereof and of the
Indenture, shall be construed in accordance with and governed by the laws of the
State of New York.

               [Trustee's Certificate of Authentication.]

         This is one of the Securities of the series designated herein referred
to in the within-mentioned Indenture.

As [Authenticating Agent for] the Trustee

By _______________________________
        Authorized Officer


                                       5