<PAGE>   1
                                                                    Exhibit 10.8


                                                                  WARRANT NO. 04

                        TASER INTERNATIONAL, INCORPORATED

                         COMMON STOCK PURCHASE WARRANT


         TASER International, Incorporated, an Arizona corporation, (the
"Company"), hereby agrees that, for value received, Bruce R. Culver, or his
assigns, is entitled, subject to the terms set forth below, to purchase from the
Company at any time or from time to time after the effective date of July 31,
2000, and before 5:00 p.m., Scottsdale, Arizona, time, on July 31, 2005, One
hundred thirty six thousand, three hundred sixty four (136,364) shares of the no
par value Common Stock of the Company (the "Common Stock"), at an exercise price
of $.55 per share, subject to adjustment as provided herein.

         1.       Exercise of Warrant. The purchase rights granted by this
Warrant shall be exercised (in minimum quantities of 100 shares) by the holder
surrendering this Warrant with the form of exercise attached hereto duly
executed by such holder, to the Company at its principal office, accompanied by
payment, in cash or by cashier's check payable to the order of the Company, of
the purchase price payable in respect of the Common Stock being purchased. If
less than all of the Common Stock purchasable hereunder is purchased, the
Company will, upon such exercise, execute and deliver to the holder hereof a new
Warrant evidencing the number of shares of Common Stock not so purchased. As
soon as practicable after the exercise of this Warrant and payment of the
purchase price, the Company will cause to be issued in the name of and delivered
to the holder hereof, or as such holder may direct, a certificate or
certificates representing the shares purchased upon such exercise. The Company
may require that such certificate or certificate contain on the fact thereof a
legend substantially as follows:

         "The transfer of the shares represented by this certificate is
         restricted pursuant to the terms of a Common Stock Purchase Warrant
         dated July 31, 2000, issued by TASER International, Incorporated, a
         copy of which is available for inspection at the offices of TASER
         International, Incorporated. Transfer may not be made except in
         accordance with the terms of the Common Stock Purchase Warrant. In
         addition, no sale, offer to sell or transfer of the shares represented
         by this certificate shall be made unless a registration statement under
         the Federal Securities Act of 1933, as amended, (the "Act"), with
         respect to such shares is then in effect or an exemption from the
         registration requirements of the Act is then in fact applicable to such
         shares."

         2.       Negotiability and Transfer. This Warrant is issued upon the
following terms, to which the holder hereof consents and agrees:

                  (a)      Until this Warrant is duly transferred on the books
         of the Company, the Company may treat the registered holder of this
         Warrant as absolute owner hereof for all purposes without being
         affected by any notice to the contrary.

                  (b)      Each successive holder of this Warrant, or of any
         portion of the rights represented thereby, shall be bound by the terms
         and conditions set forth herein.


                                  Page 1 of 8
<PAGE>   2
         3.       Anti-dilution Adjustments. If the Company shall at any time
hereafter subdivide or combine its outstanding shares of Common Stock, or
declare a dividend payable in Common Stock, the exercise price in effect
immediately prior to the subdivision, combination, or record date for such
dividend payable in Common Stock shall forthwith be proportionately increased in
the case of combination, or proportionately decreased, in the case of
subdivision or declaration of a dividend payable in Common Stock, and each share
of Common Stock purchasable upon exercise of this Warrant, immediately preceding
such event, shall be changed to the number determined by dividing the
then-current exercise price by the exercise price as adjusted after such
subdivision, combination, or dividend payable in Common Stock.

         No fractional shares of Common Stock are to be issued upon the exercise
of the Warrant, but the Company shall pay a cash adjustment in respect of any
fraction of a share which would otherwise be issuable in an amount equal to the
same fraction of the market price per share of Common Stock on the day of
exercise as determined in good faith by the Company.

         In case of any capital reorganization or any reclassification of the
shares of Common Stock of the Company, or in the case of any consolidation with
or merger of the Company into or with another corporation, or the sale of all or
substantially all of its assets to another corporation, which is effected in
such a manner that the holders of Common Stock shall be entitled to receive
stock, securities, or assets with respect to or in exchange for Common Stock,
then, as a part of such reorganization, reclassification, consolidation, merger,
or sale, as the case may be, lawful provision shall be made so that the holder
of the Warrant shall have the right thereafter to receive, upon the exercise
hereof, the kind and amount of shares of stock or other securities or property
which the holder would have been entitled to receive if, immediately prior to
such reorganization, reclassification, consolidation, merger, or sale, the
holder had held the number of shares of Common Stock which were then purchasable
upon the exercise of the Warrant. In any such case, appropriate adjustment (as
determined in good faith by the Board of Directors of the Company) shall be made
in the application of the provisions set forth herein with respect to the rights
and interest thereafter of the holder of the Warrant, to the end that the
provisions set forth herein (including provisions with respect to adjustments of
the exercise price) shall thereafter be applicable, as nearly as reasonably may
be, in relation to any shares of stock or other property thereafter deliverable
upon the exercise of the Warrant.

         When any adjustment is required to be made in the exercise price,
initial or adjusted, the Company shall forthwith determine the new exercise
price, and

         (a) prepare and retain on file a statement describing in reasonable
         detail the method used in arriving at the new exercise price; and

         (b) cause a copy of such statement to be mailed to the holder of the
         Warrant as of a date within ten (10) days after the date when the
         circumstances giving rise to the adjustment occurred.

         4.       Transferability; Registration Rights. Prior to making any
disposition of the Warrant or of any Common Stock purchased upon exercise of the
Warrant, the holder will give


                                   Page 2 of 8
<PAGE>   3
written notice to the Company describing briefly the manner of any such proposed
disposition. The holder will not make any such disposition until (i) the Company
has notified him that, in the opinion of its counsel, registration under the Act
is not required with respect to such disposition, or (ii) a registration
statement covering the proposed distribution has been filed by the Company and
has become effective. The holder then will make any disposition only pursuant to
the conditions of such opinion or registration. The Company agrees that, upon
receipt of written notice from the holder hereof with respect to such proposed
distribution, it will use its best efforts, in consultation with the holder's
counsel, to ascertain as promptly as possible whether or not registration is
required, and will advise the holder promptly with respect thereto, and the
holder will cooperate in providing the Company with information necessary to
make such determination.

         If, at any time one (1) year after the date hereof and prior to the
expiration of seven (7) years from the date hereof, the Company shall propose to
file any registration statement under the Securities Act of 1933, as amended,
covering a public offering of the Company's Common Stock and permitting the
inclusion of shares of selling shareholders, it will notify the holder hereof at
least thirty (30) days prior to each such filing and will include in the
registration statement (to the extent permitted by applicable regulation) the
Common Stock purchased by the holder or purchasable by the holder upon the
exercise of the Warrant to the extent requested by the holder hereof.
Notwithstanding the foregoing, the number of shares of the holders of the
Warrants proposed to be registered hereby shall be reduced pro rata with an
other selling shareholder (other than the Company) upon the request of the
managing underwriter of such offering. If the registration statement or offering
statement filed pursuant to such forty-five (45) day notice has not become
effective within six (6) months following the date such notice is given to the
holder hereof, the Company must again notify such holder in the manner provided
above.

         At any time one (1) year after the date hereof and prior to the
expiration of five (5) years from the date hereof, and provided that a
registration statement on Form S-3 (or its equivalent) is then available to the
Company, and on a one-time basis only, if the holders of 51 % or more of the
Warrants and the shares acquired upon exercise of the Warrants request the
registration of the shares on Form S-3 (or its equivalent), the Company shall
promptly thereafter use its best efforts to effect the registration under the
Securities Act of 1933, as amended, of such shares which such holders request in
writing to be so registered, and in a manner corresponding to the methods of
distribution described in such holders' request.



         All expenses of any such registrations referred 10 in this Section 4,
except the fees of counsel to such holders and underwriting commissions or
discounts, shall be borne by the Company.

         The Company will mail to each record holder, at the last known post
office address, written notice of any exercise of the rights granted under this
Section 4, by certified or registered mail, return receipt requested, and each
holder shall have thirty (30) days from the date of deposit of such notice in
the U.S. Mail to notify the Company in writing whether such holder wishes to
join in such exercise.


         The Company will furnish the holder hereof with a reasonable number of
copies of any prospectus included in such filings and will amend or supplement
the same as required during the period of required use thereof. The Company will
maintain the effectiveness of any registration


                                  Page 3 of 8
<PAGE>   4
statement or the offering statement filed by the Company, whether or not at the
request of the holder hereof, for at least six (6) months following the
effective date thereof.

         In the case of the filing of any registration statement, and to the
extent permissible under the Act and controlling precedent thereunder, the
Company and the holder hereof shall provide cross indemnification agreements to
each other in customary scope covering the accuracy and completeness of the
information furnished by each.

         The holder of the Warrant agrees to cooperate with the Company in the
preparation and filing of any such registration statement or offering statement,
and in the furnishing of information concerning the holder for inclusion
therein, or in any efforts by the Company to establish that the proposed sale is
exempt under the Act as to any proposed distribution.

         5.       Cashless Exercise Option.

                  (a) Provided the Company's Common Stock shall then be traded
         on an exchange or quoted by NASDAQ or otherwise traded as described in
         5(d) hereof, the holder of this Warrant shall have the right to require
         the Company to convert this Warrant (the "Conversion Right"), at any
         time from July 31, 2000 and prior to its expiration, into shares of
         Common Stock as provided for in this Section 5. Upon exercise of the
         Conversion Right, the Company shall deliver to the holder (without
         payment by the bolder of any exercise price) that number of shares of
         Common Stock equal to the quotient obtained by dividing (x), the value
         of the Warrant at the time the Conversion Right is exercised
         (determined by subtracting the aggregate exercise price for the Warrant
         Shares in effect immediately prior to the exercise of the Conversion
         Right from the aggregate Fair Market Value [as determined below] for
         the Warrant Shares immediately prior to the exercise of the Conversion
         Right), by (y), the Fair Market Value of one share of Common Stock
         immediately prior to the exercise of the Conversion Right.

                  (b) The Conversion Right may be exercised by the holder, at
         any time or from time to time, prior to its expiration, on any business
         day, by delivering a written notice (the "Conversion Notice") to the
         Company at the offices of the Company exercising the Conversion Right
         and specifying (i) the total number of shares of Stock the Warrant
         bolder will purchase pursuant to such conversation and (ii) a place and
         a date, not less than five (5) nor more than twenty (20) business days
         from the date of the Conversion Notice, for the closing of such
         purchase.

                  (c) At any closing under Section 5(b) hereof, (i) the holder
         will surrender the Warrant, (ii) the Company will deliver to the holder
         a certificate or certificates for the number of shares of Common Stock
         issuable upon such conversion, together with cash, in lieu of any
         fraction of a share, and (iii) the Company will deliver to the holder a
         new Warrant representing the number of shares, if any, with respect to
         which the Warrant shall not have been exercised.

                  (d) "Fair Market Value" of a share of Common Stock as of a
         particular date (the "Determination Date") shall mean:


                                  Page 4 of 8
<PAGE>   5
                           (i) If the Company's Common Stock is traded on an
                  exchange or is quoted on the National Association of
                  Securities Dealers, Inc., Automated Quotation ("NASDAQ")
                  National Market System, or the Small Cap Market, then the
                  average closing or last sale prices, respectively, reported
                  for the ten (10) business days immediately preceding the
                  Determination Date.

                           (ii) If the Company's Common Stock is not traded on
                  an exchange or on the NASDAQ National Market System, or the
                  Small Cap Market, but is traded in the over-the-counter
                  market, then the average of the closing bid and asked prices
                  reported for the ten (10) business days immediately preceding
                  the Determination Date.

         6.       Notices: The Company shall mail to the registered holder of
the Warrant, at his last known post office address appearing on the books of the
Company, not less than fifteen (15) days prior to the date on which (a) a record
will be taken for the purpose of determining the holders of Common Stock
entitled to dividends (other than cash dividends) or subscription rights or (b)
a record will be taken (or in lieu thereof, the transfer books will be closed)
for the purpose of determining the holders of Common Stock entitled to notice of
and to vote at a meeting of stockholders at which any capital reorganization,
reclassification of shares of Common Stock, consolidation, merger, dissolution,
liquidation, winding up, or sale of substantially all of the Company's assets
shall be considered and acted upon.

         7.       Reservation of Common Stock. A number of shares of Common
Stock sufficient to provide for the exercise of the Warrant upon the basis
herein set forth shall at all times be reserved for the exercise thereof.

         8.       Miscellaneous. Whenever reference is made herein to the issue
or sale of shares of Common Stock, the term "Common Stock" shall include any
stock of any class of the Company other than preferred stock with a fixed limit
on dividends and a fixed amount payable in the event of any voluntary or
involuntary liquidation, dissolution, or winding up of the Company.

         The Company will not, by amendment of its Articles of Incorporation or
through reorganization, consolidation, merger, dissolution, or sale of assets,
or by any other voluntary act or deed, avoid or seek to avoid the observance or
performance of any of the covenants, stipulations, or conditions to be observed
or performed hereunder by the Company, but will, at all times in good faith,
assist, insofar as it is able, in the carrying out of all provisions hereof and
in the taking of all other action which may be necessary in order to protect the
rights of the holder hereof against dilution.

         Upon written request of the holder of this Warrant, the Company will
promptly provide such holder with a then-current written list of the names and
addresses of all holders of Warrants originally issued under the terms of, and
concurrent with, this Warrant.

         The representations, warranties, and agreements herein contained shall
survive the exercise of this Warrant. References to the "holder of" include the
immediate holder of shares purchased on the


                                  Page 5 of 8
<PAGE>   6
exercise of this Warrant, and the word "holder" shall include the plural
thereof. This Common Stock Purchase Warrant shall be interpreted under the laws
of the State of Arizona.

         All shares of Common Stock or other securities issued upon the exercise
of the Warrant shall be validly issued, fully paid, and non-assessable, and the
Company will pay all taxes in respect of the issuer thereof.

         Notwithstanding anything contained herein to the contrary, the holder
of this Warrant shall not be deemed a stockholder (including no right to vote on
any matters coming before the shareholders) of the Company for any purpose
whatsoever until and unless this Warrant is duly exercised.

         IN WITNESS WHEREOF, the Company has caused this Stock Purchase Warrant
to be executed by its duly-authorized officer and the holder hereof has hereunto
set his or her hand, all effective the date and year first above written.





                          TASER International, Incorporated



                          By: /s/ Patrick W. Smith
                              --------------------------------
                              Patrick W. Smith
                          It's: Chief Executive Officer




                          /s/ Bruce R. Culver
                          ------------------------------------
                          Bruce R. Culver







                                  Page 6 of 8
<PAGE>   7
                             WARRANT EXERCISE FORM

                  To be signed only upon exercise of Warrant.


         The undersigned, the holder of the within Warrant, hereby
irrevocably elects to exercise the purchase right represented by such Warrant
for, and to purchase thereunder, _______________ shares of Common Stock of
Taser International, Incorporated, to which such Warrant relates and herewith
makes payment of $ ________________ therefor in cash or by certified check,
and requests that such shares be issues and be delivered to_________________,
the address for which is set forth below the signature of the undersigned.


Date:_____________________________


_____________________________               ____________________________________
(Taxpayer's I.D. Number)                    (Signature)


                                            ____________________________________

                                            ____________________________________
                                            (Address)





                                 ASSIGNMENT FORM

             To be signed only upon authorized transfer of Warrant.


         FOR VALUE RECEIVED, the undersigned hereby sells, assigns, and
transfers unto __________________ the right to purchase shares of Common Stock
of Taser International, Incorporated, to which the within Warrant relates and
appoints ________________ attorney, to transfer said right on the books of Taser
International, Incorporated, with full power of substitution in the premises.


Date:_____________________________




                                            ____________________________________
                                            (Signature)


                                            ____________________________________

                                            ____________________________________
                                            (Address)






                                  Page 7 of 8
<PAGE>   8
                             CASHLESS EXERCISE FORM

        (To be executed upon exercise of Warrant pursuant to Section 5.)

         The undersigned hereby irrevocably elects a cashless exercise of the
right of purchase represented by the within Common Stock Purchase Warrant for,
and to purchase thereunder, ______________ shares of Common Stock, as provided
for in Section 5 therein.

         If said number of shares shall not be all the shares purchasable under
the within Common Stock Purchase Warrant, a new Warrant is to be issued in the
name of said undersigned for the balance remaining of the shares purchasable
thereunder rounded up to the next higher number of shares.

         Please issue a certificate or certificates for such Common Stock in the
name of, and pay any cash for any fractional shares to:

NAME:           ___________________________________________
                (Please Print Name)


ADDRESS:        ___________________________________________

                ___________________________________________



SOCIAL SECURITY NUMBER:    ________________________________


SIGNATURE:                 ________________________________


         NOTE: The above signature should correspond exactly with the name on
         the first page of this Common Stock Purchase Warrant or with the name
         of the assignee appearing in the assignment form on the preceding page.




                                  Page 8 of 8