EXHIBIT 10.42

THIS NOTE AND ANY SHARES  ACQUIRED  UPON  CONVERSION  OF THIS NOTE HAVE NOT BEEN
REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), AND MAY NOT
BE SOLD,  TRANSFERRED,  ASSIGNED OR  HYPOTHECATED  UNLESS  THERE IS AN EFFECTIVE
REGISTRATION  STATEMENT  UNDER SUCH ACT COVERING THIS NOTE,  THE SALE IS MADE IN
ACCORDANCE  WITH RULE 144 UNDER THE ACT, OR THE  COMPANY  RECEIVES AN OPINION OF
COUNSEL  FOR THE HOLDER OF THIS NOTE  REASONABLY  SATISFACTORY  TO THE  COMPANY,
STATING THAT SUCH SALE, TRANSFER, ASSIGNMENT OR HYPOTHECATION IS EXEMPT FROM THE
REGISTRATION AND PROSPECTUS DELIVERY REQUIREMENTS OF SUCH ACT.


                    GUARDIAN TECHNOLOGIES INTERNATIONAL, INC.
                           CONVERTIBLE PROMISSORY NOTE

Note Amount:  $ 200,000                                        December 19, 2003


      Guardian  Technologies  International,  Inc., a Delaware  corporation (the
"Company"),  for value received, hereby promises to pay to Edward D. Tschiggfrie
("Holder"),  the principal  sum of Two Hundred  Thousand  Dollars  $200,000 with
interest as provided below. The Company agrees that proceeds under this Note may
only be used for the expressed purpose as defined in "Allowed Use of Proceeds."

      1.    Payment.

            a.    Payment.  Subject  to  the  provisions  of  Section  3  hereof
                  relating to the conversion of this Note, principal and accrued
                  interest hereof shall be payable sixty (60) days from the date
                  of this Note (the "Maturity Date").  Payments  hereunder shall
                  be  made by the  Company  to the  Holder,  at the  address  as
                  provided to the  Company by the Holder in  writing,  in lawful
                  money of the United States of America.  Interest  shall accrue
                  with respect to the unpaid  principal  amount of the loan from
                  the date of this Note until the  Maturity  Date at a flat rate
                  of ten  percent  (10%)  or  $20,000.  Interest  at a  rate  of
                  eighteen (18%) percent per annum,  computed on a 365 day year,
                  will be accrued to the  outstanding  principal  and  interest,
                  beginning on the sixty-first (61st) day and until such time as
                  the  principal  and interest have been repaid or converted per
                  Section 3(b).

            b.    Prepayment.  The Company  shall have the right at any time and
                  without penalty to prepay,  in whole or in part, the principal
                  outstanding and/or the interest accrued hereunder.

      2.    Certain Definitions.

            a.    "Allowed   Use  of   Proceeds"   shall  mean  solely  for  the
                  acquisition of the MCubiX source code from Diagnos, Inc.

            b.    "Bridge  Notes" shall mean the series of notes,  of which this
                  Note is a part,  dated on or about  the date  hereof,  each of
                  which  are  identical,  other  than  the  date of the Note and
                  identity of the Holder.


<PAGE>


            c.    "Financing"  shall  mean the  first  closing  of the  proposed
                  Private  Placement  offered  through  Berthel Fisher & Company
                  Financial Services.

            d.    "Financing   Securities"  shall  mean  the  shares  of  equity
                  securities   of  the  Company  sold  in  the   Financing.

            e.    "Obligations" shall mean all outstanding principal and accrued
                  interest due hereunder.

3.    Obligations Upon Failure to Acquire MCubiX Source Code.

      a.    Should the Company,  within forty-five (45) days of the date of this
            Note, be unsuccessful in its negotiations for the acquisition of the
            MCubiX  source  code,  the Holder shall be entitled to the return of
            principal  plus the interest  under  Section  1(a) above.  This will
            constitute  full  payment  and   satisfaction  of  this  Convertible
            Promissory  Note.  However,  the  Holder  may elect to  convert  the
            principal  and  interest  (in full or in part)  under  the terms and
            conditions as described in Section 4 below.

      b.    If at any time before  January  16,  2004,  the  Company  shall have
            reached an agreement in principle for the  acquisition of the MCubiX
            source  code,  yet  ultimately  fails  to  consummate  a  Definitive
            Agreement for the  acquisition,  the Holder shall be entitled to the
            following:  (i) return of principal  plus the interest under Section
            1(a) above,  and (ii) Series A Common Stock  Warrants (as defined in
            the Common Stock Purchase Warrant Agreement) equal to 1,000 warrants
            for each  business  day  between  January  16, 2004 and the date the
            Company  terminates its  negotiations  for the acquisition of MCubiX
            source code. This will  constitute full payment and  satisfaction of
            this Convertible  Promissory Note. However,  the Holder may elect to
            convert the  principal  and  interest (in full or in part) under the
            terms and conditions as described in Section 4 below.

4.    Conversion.

      a.    Conversion Upon Financing.  This Note shall convert, at the Holder's
            option,  into  the  Financing  Securities  upon the  closing  of the
            Financing. The Holder may elect to convert 100% of the principal and
            interest due, or any part thereof.  The Holder is hereby granted the
            right to convert  this note into the  Financing  on a last dollar in
            basis.  The Holder is  guaranteed  a  participatory  position in the
            Financing.

      b.    Conversion  Upon  Available  Funds in  Escrow.  To the  extent  that
            sufficient  funds to repay the  outstanding  principal  and  accrued
            interest have been deposited in escrow as part of the Financing, but
            have  not  closed  by the  Maturity  Date,  the  Holder  shall  earn
            additional interest on the outstanding principal and interest at the
            interest  rate  described in Section 1(a) above.  In addition to the
            interest on the Note,  the Holder shall be entitled to receive Eight
            Thousand (8,000) stock purchase  warrants for every thirty (30) days
            the Note is outstanding beyond the Maturity Date, granting the right
            to purchase one share of Common Stock for each warrant issued,  at a
            price of $2.50 per share.  The stock purchase  warrants shall expire
            eighteen months after the issue date of the warrants. Closing of the
            funds in escrow must occur  within the thirty (30) days  immediately
            following the Maturity Date of the Note.

      c.    Conversion  Absent  Financing within sixty (60) days of execution of


                                       2
<PAGE>


            this Note.  If no Financing  shall have  occurred  within sixty (60)
            days of the  execution  of this  Note,  then  the  Holder  shall  be
            entitled to Eighty  Thousand  (80,000) stock warrants  entitling the
            Holder to purchase  one share of Common  Stock for each warrant at a
            price of $2.50 per share.  The warrants  shall have an eighteen (18)
            month expiration. The Holder may elect to convert all or part of the
            amount owing under this Note.  The stock  purchase  warrants will be
            allocated on a pro rata basis to the shares converted.

      d.    Conversion  Price  Upon  Financing.  In the  event  of a  conversion
            pursuant  to  subsection  3(a)  hereof,  the number of shares of the
            Financing Securities to be issued upon conversion of the Obligations
            shall equal the aggregate  amount of the Obligations  divided by the
            price per share of the Financing  Securities  issued and sold in the
            Financing plus any other considerations contained in the Financing.

      e.    Conversion  Price  Absent  Financing.  In the event of a  conversion
            pursuant to subsections 3(b) or 3(c) hereof, the number of shares of
            the Common  Stock to be issued  upon  conversion  of this Note shall
            equal the aggregate amount of the Obligations divided by $1.50.

      f.    Notice Regarding Financing. Written notice shall be delivered to the
            Holder of this Note at the  address so  indicated  on the  execution
            page of the Note and Warrant Purchase Agreement notifying the Holder
            of the  terms  and  conditions  of  the  Financing,  the  applicable
            conversion  price,  the date on which a  conversion  may  occur  and
            calling  upon such Holder to  surrender  the Note to the Company for
            cancellation and conversion/repayment in the manner and at the place
            designated.

      g.    Mechanics  and  Effect  of  Conversion.   No  fractional  shares  of
            Financing Securities or Common Stock shall be issued upon conversion
            of this Note.  Notwithstanding  any other  provision of this Note or
            the Note and  Common  Stock  Warrant  Purchase  Agreement,  upon the
            conversion  of the  Obligations  under  this  Note,  in  lieu of the
            Company  issuing any  fractional  shares to the Holder,  the Company
            shall pay to the Holder in cash the amount of the  Obligations  that
            is not so converted.  Upon conversion of this Note pursuant  hereto,
            the  Holder  shall  surrender  this  Note,  duly  endorsed,  at  the
            principal  office of the Company and shall execute such documents as
            are  reasonably  required to be executed  by all  purchasers  of the
            Financing  Securities.  The Company  shall,  as soon as  practicable
            thereafter,  issue and  deliver  to such  Holder  at such  principal
            office a certificate or certificates for the number of shares of the
            Financing  Securities  or Common  Stock to which the Holder shall be
            entitled upon such conversion  (bearing such legends as are required
            by applicable  state and federal  securities  laws in the opinion of
            counsel to the  Company),  together  with any other  securities  and
            property to which the Holder is entitled upon such conversion  under
            the terms of this Note.  Upon full  conversion of this Note pursuant
            to the terms hereof,  the Company shall be forever released from all
            its obligations and liabilities  under this Note. Upon conversion of
            this Note into  Financing  Securities  or Common  Stock,  the Holder
            shall be  entitled  to all rights  and  privileges  afforded  by the
            Company to other  holders  of such  Financing  Securities  or Common
            Stock.

5.    Events of Default. The occurrence of any of the following shall constitute
      an "Event  of  Default"  under  this  Note and the Note and  Common  Stock
      Warrant   Purchase   Agreement  of  even  date  herewith  (the   "Purchase
      Agreement"):


                                       3
<PAGE>


      a.    Failure  to Pay.  The  Company  shall  fail to pay (i)  when due any
            principal  payment on the due date hereunder or (ii) any interest or
            other payment  required under the terms of this Note on the date due
            and such payment  shall not have been made within  fifteen (15) days
            of Company's  receipt of Holder's  written  notice to the Company of
            such failure to pay; or

      b.    Voluntary  Bankruptcy or Insolvency  Proceedings.  The Company shall
            (i) apply for or consent to the appointment of a receiver,  trustee,
            liquidate or custodian of itself or of all or a substantial  part of
            its property,  (ii) make a general assignment for the benefit of its
            or any of its creditors, (iii) be dissolved or liquidated in full or
            in part, (iv) commence a voluntary case or other proceeding  seeking
            liquidation,  reorganization  or other relief with respect to itself
            or its debts under any  bankruptcy,  insolvency or other similar law
            now or  hereafter  in effect or consent to any such relief or to the
            appointment of or taking  possession of its property by any official
            in an involuntary case or other proceeding  commenced against it, or
            (v)  take  any  action  for  the  purpose  of  effecting  any of the
            foregoing; or

      c.    Involuntary  Bankruptcy or Insolvency  Proceedings.  Proceedings for
            the appointment of a receiver,  trustee,  liquidator or custodian of
            the Company or of all or a substantial part of the property thereof,
            or an involuntary  case or other  proceedings  seeking  liquidation,
            reorganization  or other  relief with  respect to the Company or the
            debts thereof under any bankruptcy,  insolvency or other similar law
            or hereafter  in effect  shall be commenced  and an order for relief
            entered or such  proceeding  shall not be  dismissed  or  discharged
            within thirty (30) days of commencement.

6.    Rights of Holder Upon  Default.  Upon the  occurrence  or existence of any
      Event of Default (other than an Event of Default referred to in Paragraphs
      4(c) and at any time  thereafter  during the  continuance of such Event of
      Default, Holder may declare all outstanding Obligations payable by Company
      hereunder to be immediately due and payable without  presentment,  demand,
      protest or any other notice of any kind, all of which are hereby expressly
      waived,  anything  contained  herein or in the  Purchase  Agreement to the
      contrary notwithstanding. Upon the occurrence or existence of any Event of
      Default described in Paragraphs 4(c),  immediately and without notice, all
      outstanding  Obligations  payable by Company hereunder shall automatically
      become immediately due and payable,  without presentment,  demand, protest
      or any other notice of any kind, all of which are hereby expressly waived,
      anything  contained  herein or in the  Purchase  Agreement to the contrary
      notwithstanding.   In  addition  to  the  foregoing  remedies,   upon  the
      occurrence  or existence of any Event of Default,  Holder may exercise any
      other right,  power or remedy  granted to it by the Purchase  Agreement or
      otherwise permitted to it by law, either by suit in equity or by action at
      law, or both.

7.    Miscellaneous.

      a.    Amendment  Provisions.  Any  provision  of this Note  other than the
            principal  amount and identity of the Holder may be amended,  waived
            or modified upon the written  consent of the Company and the parties
            providing  at least a majority of the  aggregate  principal  amounts
            provided pursuant to the Bridge Notes.

      b.    Severability.  If any  provision  of this Note is  determined  to be
            invalid,  illegal  or  unenforceable,  in  whole  or  in  part,  the
            validity,  legality  and  enforceability  of any  of  the  remaining
            provisions or portions of this Note shall not in any way be affected


                                       4
<PAGE>


            or  impaired  thereby  and this Note shall  nevertheless  be binding
            between the Company and the Holder.

      c.    Governing  Law.  This Note shall be  governed  by and  construed  in
            accordance with the laws of the State of Delaware.

      d.    Binding Effect.  This Note shall be binding upon, and shall inure to
            the  benefit  of, the  Company  and the Holder and their  respective
            successors and assigns; provided,  however, that the Company may not
            assign its obligations  hereunder without the Holder's prior written
            consent.

      e.    Enforcement Costs. The Company agrees to pay all costs and expenses,
            including,  without  limitation,   reasonable  attorneys'  fees  and
            expenses,  the  Holder  expends  or  incurs in  connection  with the
            enforcement  of this Note, the collection of any sums due hereunder,
            any actions for declaratory  relief in any way related to this Note,
            or the  protection  or  preservation  of any  rights  of the  Holder
            hereunder.

      f.    Notices.  Any  notice,  request or other  communication  required or
            permitted hereunder shall be in writing and shall be duly given upon
            receipt if personally delivered or mailed by registered or certified
            mail,  postage  prepaid,  or  by  recognized  overnight  courier  or
            personal  delivery,  addressed  (i) if to Holder,  at the address or
            facsimile number of such Holder as set forth below such party's name
            on Exhibit A to the Purchase Agreement,  or at such other address or
            number  as such  Holder  shall  have  furnished  to the  Company  in
            writing, or (ii) if to Company, at 21351 Ridgetop Circle, Suite 300,
            Dulles,  Virginia 20166,  Attention:  Chief Financial  Officer or at
            such other  address as Company  shall  furnish to the  Purchaser  in
            writing.

      g.    Payment.  Payment  shall  be made in  lawful  tender  of the  United
            States.

      h.    Transfer of Note or Securities  Issuable on Conversion Hereof.  This
            Note or the  securities  issuable  on  conversion  hereof may not be
            transferred in violation of any restrictive  legend set forth hereon
            or thereon.  Each new Note issued  upon  transfer of this Note,  and
            each  security  issuable  on  conversion  hereof,   shall  bear  the
            restrictive legend set forth below, unless in the opinion of counsel
            for  Company  such  legend  is  not  required  in  order  to  ensure
            compliance with the Act:


"THE SHARES  REPRESENTED BY THIS  CERTIFICATE  HAVE NOT BEEN REGISTERE UNDER THE
SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT BE SOLD OR OTHERWISE TRANSFERRED
EXCEPT PURSUANT TO AN EFFECTIVE  REGISTRATION  STATEMENT FILED UNDER SUCH ACT OR
PURSUANT TO AN EXEMPTION FROM REGISTRATION UNDER SUCH ACT."

The  Company  may issue stop  transfer  instructions  to its  transfer  agent in
connection with such restrictions.  Subject to the foregoing,  transfers of this
Note shall be registered upon registration  books maintained for such purpose by
or on behalf of the  Company as  provided in the  Purchase  Agreement.  Prior to
presentation of this Note for registration of transfer,  the Company shall treat
the  registered  holder  hereof  as the  owner  and  holder of this Note for the
purpose of receiving all payments of principal  and interest  hereon and for all
other purposes whatsoever, whether or not this Note shall be overdue and Company
shall not be affected by notice to the contrary.


                                       5
<PAGE>


      i.    Headings.  Section  headings  used in this  Note have been set forth
            herein for  convenience  of reference  only.  Unless the contrary is
            compelled  by the  context,  everything  contained  in each  section
            hereof applies equally to this entire Note.


      IN WITNESS  WHEREOF,  the  Company has caused this Note to be issued as of
the date first written above.

                                     Guardian Technologies International, Inc.



                                     By:______________________________________
                                     Name: Michael W. Trudnak
                                     Title: Chairman and Chief Executive Officer



                                       6