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                                                                    EXHIBIT 4.21

                                    EXHIBIT A

THIS NOTE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED
(THE "ACT"), OR UNDER ANY STATE SECURITIES LAW OF ANY STATE OR OTHER
JURISDICTION AND MAY NOT BE SOLD, ASSIGNED, PLEDGED, HYPOTHECATED OR OTHERWISE
TRANSFERRED IN THE ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT FOR THIS NOTE
UNDER THE ACT AND APPLICABLE SECURITIES LAWS OF ANY STATE OR OTHER JURISDICTION,
OR AN OPINION OF COUNSEL SATISFACTORY TO MAKER THAT SUCH REGISTRATION IS NOT
REQUIRED.

                           MOBILITY ELECTRONICS, INC.

                           13% BRIDGE PROMISSORY NOTE

                                  NO. BN - ____

$____________                                                _____________,1999


     FOR VALUE RECEIVED, the undersigned, Mobility Electronics, Inc., a Delaware
corporation ("Maker"), hereby promises to pay to the order of
__________________________, or its successors or assigns ("Payee"), the
principal sum of ____________________ and No/100 Dollars ($_______________),
together with interest accrued thereon (calculated on the basis of a 365-day
year) at a rate of thirteen percent (13%) per annum from the date hereof until
the date that this Note is paid in full; provided, however, that such interest
rate shall increase to a rate of eighteen percent (18%) per annum upon the
occurrence, and during the continuation, of an Event of Default (as defined
below). All payments on this Note shall be due and payable in lawful money of
the United States of America.

     This Note is one of a series of promissory notes of the Company styled "13%
Bridge Promissory Note" in the aggregate amount not to exceed $2,500,000 (plus
an over-allotment option not to exceed $500,000), which are being issued from
time to time between February 24, 1999 and March 5, 1999, subject to a one-week
extension at the option of Maker (collectively, the "Bridge Notes").

     1. Principal and Interest Payments. The principal of and interest on this
Note shall be due and payable on March 5, 2000. Maker agrees that any payments
of interest and/or principal on the Bridge Notes (including this Note) shall be
made pari passu with all Bridge Notes based on the principal balance and the
accrued but unpaid interest on all Bridge Notes at the time of such payment.


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     2. Prepayments. Neither the unpaid principal balance of this Note nor any
accrued but unpaid interest thereon may be prepaid in whole or in part without
the prior written consent of Payee (and in any event, subject to Section 1
above).

     3. Method of Payment. All payments made under this Note, whether of
principal or interest, shall be made by Maker to the holder hereof on the date
specified or provided herein and shall be delivered by means of certified or
cashiers' check or wire transfer of immediately available funds to an account
specified by the holder hereof. Whenever payment hereunder shall be due on a day
which is not a Business Day (as hereinafter defined), the date for payment
thereof shall be extended to the next succeeding Business Day. If the date for
any payment is extended by operation of law or otherwise, interest thereon shall
be payable for such extended time. "Business Day" means every day which is not a
Saturday, Sunday or legal holiday.

     4. Subordination. Notwithstanding anything herein to the contrary, the
payment of principal of and interest on this Note shall be subordinate and
junior to the prior payment of the indebtedness of Maker: (a) owed to Sirrom
Capital Corporation and NationsBank, N.A., and their respective successors and
assigns (as such indebtedness may be renewed, deferred, extended, refunded,
amended or modified from time to time); and (b) hereafter created constituting
borrowed money from financial institutions or lenders approved by the Board of
Directors of Maker and designated in writing as being senior to this Note (but
only to the extent so designated (as such indebtedness may be renewed, deferred,
extended, refunded, amended or modified from time to time) (collectively, the
"Senior Indebtedness"). If any payment or distribution shall be received in
respect of this Note in contravention of the terms of this Section 4, such
payment or distribution shall be held in trust for the holders of the Senior
Indebtedness, and shall be immediately delivered to such holders in the same
form as received.

     5. Events of Default. The following shall constitute events of default
("Events of Default") hereunder:

          (a) failure of Maker to make any payment on this Note as and when the
same becomes due and payable in accordance with the terms hereof;

          (b) failure of Maker to perform any other covenant contained herein,
if the same has continued for thirty (30) days after written notice specifying
such default has been delivered to Maker by Payee;

          (c) the occurrence of any event of default under any Bridge Note or
under the Senior Indebtedness, which event of default is not cured within any
applicable cure period and, in the case of Senior Indebtedness, for which the
holder of such Senior Indebtedness commences legal action against Maker to
collect the Senior Indebtedness;

          (d) if Maker makes an assignment for the benefit of creditors, or
petitions or applies for the appointment of a liquidator, receiver or custodian
(or similar official) of it or of any


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substantial part of its assets, or if Maker commences any proceeding or case
relating to it under the Bankruptcy Code or any other bankruptcy,
reorganization, arrangement, insolvency, readjustment of debt, dissolution or
liquidation or similar law of any jurisdiction, or takes any action to authorize
any of the foregoing; or

          (e) if any petition or application of the type described in
subparagraph (e) immediately above is filed or if any such proceeding or case
described in subparagraph (e) is commenced against Maker and is not dismissed
within sixty (60) days, or if Maker indicates its approval thereof, consents
thereto or acquiesces therein, or if an order is entered appointing any such
liquidator or receiver or custodian (or similar official), or adjudicating Maker
bankrupt or insolvent, or approving a petition in any such proceeding, or if a
decree or order for relief is entered in respect of Maker in an involuntary case
under the Bankruptcy Code or any other bankruptcy, reorganization, arrangement,
insolvency, readjustment of debt, dissolution or liquidation or similar law of
any jurisdiction.

     In the event any one or more of the Events of Default specified above
occurs and is continuing, the holder of this Note may (i) accelerate the
maturity of this Note with notice to Maker at which time all such amounts shall
be immediately due and payable, (ii) proceed to protect and enforce its rights
either by suit in equity or by action at law, or by other appropriate
proceedings, whether for the specific performance of any covenant or agreement
contained in this Note or in aid of the exercise of any power or right granted
by this Note, or (iii) enforce any other legal or equitable right of the holder
of this Note.

     6. Delay or Omission Not Waiver. No delay or omission on the part of the
holder of this Note in the exercise of any power, remedy or right under this
Note, or under any other instrument executed pursuant hereto, shall operate as a
waiver thereof, nor shall a single or partial exercise of any such power or
right preclude any other or further exercise thereof or the exercise of any
other right or power hereunder.

     7. Waiver. Any term, covenant, agreement or condition of this Note may,
only with the written consent of Maker and Payee, be amended or compliance
therewith may be waived (either generally or in a particular instance and either
retroactively or prospectively), altered, modified or amended.

     8. Attorneys' Fees and Costs. In the event an Event of Default shall occur,
and in the event that thereafter this Note is placed in the hands of an attorney
for collection, or in the event this Note is collected in whole or in part
through legal proceedings of any nature, then and in any such case Maker
promises to pay all costs of collection, including, but not limited to,
reasonable attorneys' fees and court costs incurred by the holder hereof on
account of such collection, whether or not suit is filed.


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     9. Successors and Assigns. All of the covenants, stipulations, promises and
agreements in this Note made by Maker and Payee (by virtue of its acceptance of
this Note) shall bind its successors and assigns, whether so expressed or not.

     10. Maximum Lawful Rate. It is the intent of the Maker and holder of this
Note to conform to and contract in strict compliance with applicable usury law
from time to time in effect. In no way, nor in any event or contingency
(including but not limited to prepayment, default, demand for payment, or
acceleration of the maturity of any obligation), shall the rate of interest
taken, reserved, contacted for, charged or received under this Note exceed the
highest lawful interest rate permitted under applicable law. If the holder of
this Note shall ever receive anything of value which is characterized as
interest under applicable law and which would apart from this provision be in
excess of the highest lawful interest rate permitted under applicable law, an
amount equal to the amount which would have been excessive interest shall,
without penalty, be applied to the reduction of the principal amount owing on
this Note in the inverse order of its maturity and not to the payment of
interest, or refunded to Maker or the other payor thereof if and to the extent
such amount which would have been excessive exceeds such unpaid principal. All
interest paid or agreed to be paid to the holder hereof shall, to the extent
permitted by applicable law, be amortized, prorated, allocated and spread
throughout the full stated term (including any renewal or extension) of this
Note so that the amount of interest on account of such obligation does not
exceed the maximum permitted by applicable law. As used in this Section, the
term "applicable law" shall mean the laws of the State of Delaware or the
federal laws of the United States, whichever laws allow the greater interest, as
such laws now exist or may be changed or amended or come into effect in the
future.

     11. Governing Law. This Note shall be governed by and construed in
accordance with the substantive laws (but not the rules governing conflicts of
laws) of the State of Delaware.

     12. Notice. All notices, demands or requests provided for or permitted to
be given under this Note must be in writing, and shall be given and be deemed
received as set forth in the Purchase Agreement.

     13. Severability. In case any one or more of the provisions contained in
this Note shall for any reason be held to be invalid, illegal or unenforceable
in any respect, such invalidity, illegality or unenforceability shall not affect
any other provision hereof.


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     EXECUTED as of the date set forth above.

                                          MAKER:

                                          MOBILITY ELECTRONICS, INC.


                                          By:
                                              ---------------------------------
                                              Charles R. Mollo,
                                              Chief Executive Officer




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