EXHIBIT
      10.13








**THIS
      NOTE AND THE SECURITIES ISSUABLE HEREUNDER HAVE NOT BEEN REGISTERED UNDER THE
      SECURITIES ACT OF 1933, AS AMENDED (THE “** **SECURITIES
      ACT** **”),
      OR ANY STATE SECURITIES LAWS AND MAY NOT BE OFFERED, SOLD, PLEDGED, OR OTHERWISE
      TRANSFERRED OR DISPOSED OF UNLESS AND UNTIL THIS NOTE AND/OR SUCH SECURITIES
      ARE
      REGISTERED UNDER THE SECURITIES ACT AND APPLICABLE STATE SECURITIES LAWS OR
      AN
      EXEMPTION FROM SUCH REGISTRATION IS AVAILABLE.**





**CONVERTIBLE
      PROMISSORY NOTE**








**$400,000**
            **December****23****,
                2005**





FOR
      VALUE
      RECEIVED, the undersigned, GABRIEL TECHNOLOGIES CORPORATION, a Delaware
      corporation (“ Maker ”),
      promises to pay to the order of CTSL INVESTMENT, LLC, an Iowa limited liability
      company (“ Payee ”),
      the
      principal sum of Four Hundred Thousand Dollars ($400,000) (the “ Principal ”),
      plus
      an amount equal to 150% of the principal sum (the “ Note
      Obligation ”).
      All
      amounts due under this Note shall be payable as and at such time or times as
      are
      set forth in Paragraph 1 hereof. All payments on this Note shall be due and
      payable in lawful money of the United States of America at 675 South Fork Drive,
      Des Moines, Iowa 50263 ** (or
      such
      other place as Payee may from time to time designate in writing).





1.  Payments .
      The
      Principal and the Note Obligation shall become due and payable on December
      31,
      2006. Payment hereunder shall terminate the right to convert this Note. This
      Note shall be prepayable by the Maker as set forth in Paragraph 3
      hereof.





2.  Events
      of Default and Remedies .
      In the
      event Maker fails to pay any amount due under this Note within ten Business
      Days
      (as hereafter defined) after such amount is due, the holder of this Note may
      (i)
      offset against this Note any sum or sums owed by the holder hereof to Maker,
      or
      (ii) proceed to protect and enforce his rights either by suit in equity and/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 to enforce
      any other legal or equitable right of the holder of this Note. As used herein,
      a
“ Business
      Day ”
is
      any
      day other than a Saturday, Sunday or a legal holiday for financial institutions
      in Omaha, Nebraska.





3.  Prepayments .
      The
      Principal and Note Obligation on this Note may be voluntarily prepaid in whole
      or in part at any time prior to conversion of this Note in accordance with
      Section 4 hereof. At any time prior to payment of the Principal and Note
      Obligation on this Note, the holder hereof shall have the option of exercising
      its Optional Conversion rights under Section 4(a), and Maker shall have the
      option of exercising its Mandatory Conversion rights under Section
      4(c).


-1-


4.  Conversion .





(a)  *Conversion
      by Payee.* Unpaid
      Principal and Note Obligation on this Note shall be convertible at the option
      of
      Payee or other holder hereof (the “ Optional
      Conversion ”),
      at
      any time, in whole or in part, in lieu of and in satisfaction of such unpaid
      Principal and unpaid Note Obligation. This Note shall be convertible into that
      number of fully paid and nonassessable shares of Common Stock (as defined in
      Section 5) as is equal to the quotient of the unpaid Principal plus the unpaid
      Note Obligation divided by the applicable Conversion Price (as defined in
      Section 5) ** in
      effect
      from time to time. Upon any Optional Conversion, the outstanding Principal
      and
      unpaid Note Obligation due under this Note shall be reduced in full by an amount
      equal to the number of shares of Common Stock issued upon such conversion
      multiplied by the applicable Conversion Price.





(b)  *Conversion
      Procedures.* If
      Payee
      desires to convert this Note into Common Stock, it shall surrender this Note
      to
      Maker at its principal executive offices, accompanied by proper instruments
      of
      transfer to Maker or in blank, accompanied by irrevocable written notice
      (“Optional Conversion Notice”) to Maker that Payee elects so to convert this
      Note and the name or names (with address) in which a certificate or certificates
      for Common Stock are to be issued. Maker shall, as soon as practicable after
      such written notice and compliance with any other conditions herein contained,
      deliver at such office to Payee, certificates for the number of full shares
      of
      Common Stock to which it shall be entitled. Such conversion shall be deemed
      to
      have been made as of the date of such surrender of this Note, and the person
      or
      persons entitled to receive Common Stock or other securities deliverable upon
      conversion shall be treated for all purposes as the record holder or holders
      thereof on such date.





(c)  *Conversion
      by Maker.* Notwithstanding
      anything to the contrary in this Note, up to the entire amount of the unpaid
      Principal and Note Obligation on the Note may be converted at the Maker’s
      election (“Mandatory Conversion”) provided: (i) no event of default has occurred
      and is continuing; (ii) the closing sales price of the Common Stock on its
      principal trading market for ten consecutive trading days (the “Trading Period”)
      is greater than 150% of the Maximum Conversion Price on each trading day during
      the Trading Period; **[and
      (iii) the Common Stock issuable upon conversion of the then-outstanding
      principal and unpaid Note Obligation are included for unrestricted resale in
      a
      registration statement effective as of the date notice is given by the Maker
      to
      the holder of its election to convert the Note pursuant to this Section 4(c)
      (“Mandatory Conversion Notice”) and through the date the shares issuable upon
      Mandatory Conversion of the Note are delivered to such
      holder.]** The
      Mandatory Conversion Notice must be given no later than the third trading day
      following the Trading Period. This Note shall be convertible into that number
      of
      fully paid and nonassessable shares of Common Stock (as defined in Section
      5) ** as
      is
      equal to the quotient of the unpaid Principal plus the unpaid Note Obligation
      divided by the applicable Conversion Price (as defined in Section 5) ** in
      effect
      from time to time. Upon any Mandatory Conversion, the outstanding Principal
      and
      unpaid Note Obligation due under this Note shall be reduced in full by an amount
      equal to the number of shares of Common Stock issued upon such conversion
      multiplied by the applicable Conversion Price. If Maker desires to effect a
      Mandatory Conversion of all or part of this Note into Common Stock, it shall
      provide the Mandatory Conversion Notice to the holder of this Note. Maker shall,
      within five Business Days thereafter, deliver to the holder of this Note (in
      exchange therefor) certificates for the number of full shares of Common Stock
      to
      which it shall be entitled. Such conversion shall be deemed to have been made
      as
      of the date of the Mandatory Conversion Notice, and the person or persons
      entitled to receive Common Stock or other securities deliverable upon conversion
      shall be treated for all purposes as the record holder or holders thereof on
      such date.


-2-


(d)  *Certain
      Adjustments.* The
      applicable Conversion Price and the number of securities issuable upon
      conversion of this Note shall be subject to adjustment from time to time as
      follows:





(i)  In
      case
      Maker shall at any time after the date hereof (1) pay a dividend or make a
      distribution on its capital stock that is paid or made in shares of stock of
      Maker, (2) subdivide its outstanding shares of Common Stock into a greater
      number of shares or (3) combine its outstanding shares of Common Stock into
      a
      smaller number of shares, then in each such case the applicable Conversion
      Price
      in effect immediately prior thereto and the securities issuable shall be
      adjusted retroactively as provided below so that Payee thereafter shall be
      entitled to receive the number of shares of Common Stock of Maker and other
      shares and rights to purchase stock or other securities which Payee would have
      owned or have been entitled to receive after the happening of any of the events
      described above had this Note been converted immediately prior to the happening
      of such event or any record date with respect thereto. In the event of the
      redemption of any shares referred to in clause (1), Payee shall have the right
      to receive, in lieu of any such shares or rights, any cash, property or
      securities paid in respect of such redemption. An adjustment made pursuant
      to
      this subparagraph (i) shall become effective immediately after the record date
      in the case of a dividend or distribution and shall become effective immediately
      after the effective date in the case of a subdivision or
      combination.





(ii)  Whenever
      the Conversion Price is adjusted as provided above, Maker shall compute the
      adjusted Conversion Price in accordance herewith and mail to Payee a notice
      stating that the Conversion Price has been adjusted and setting forth the
      adjusted Conversion Price.





(iii)  In
      the
      event that at any time, as a result of any adjustment made pursuant to this
      Section, Payee shall become entitled to receive any shares of Maker other than
      shares of Common Stock or to receive any other securities, the number of such
      other shares or securities so receivable upon conversion of this Note shall
      be
      subject to adjustment from time to time in a manner and on terms as nearly
      equivalent as practicable to the provisions contained in these provisions with
      respect to Common Stock.





(e)  *No
      Fractional Shares.* No
      fractional shares or scrip representing fractional shares of Common Stock shall
      be issued upon conversion of this Note. All calculations of the number of shares
      of Common Stock to be issued upon conversion of this Note shall be rounded
      to
      the nearest whole share.


-3-


(f)  *Reclassification,
      Consolidation, Merger or Sale of Assets.* In
      case
      of any reclassification of Common Stock, any consolidation of Maker with, or
      merger of Maker into, any other person, any merger of another person into Maker
      (other than a merger which does not result in any reclassification, conversion,
      exchange or cancellation of outstanding shares of Common Stock of Maker), any
      sale or transfer of all or substantially all of the assets of Maker or any
      compulsory share exchange pursuant to which share exchange the Common Stock
      is
      converted into other securities, cash or other property, then lawful provision
      shall be made as part of the terms of such transaction whereby Payee shall
      have
      the right thereafter, during the period this Note shall be convertible
      hereunder, to convert this Note only into the kind and amount of securities,
      cash and other property receivable upon such reclassification, consolidation,
      merger, sale, transfer or share exchange by a holder of the number of shares
      of
      Common Stock of Maker into which this Note might have been converted immediately
      prior to such reclassification, consolidation, merger, sale, transfer or share
      exchange assuming such holder of Common Stock of Maker (i) is not a person
      with
      which Maker consolidated or into which Maker merged or which merged into Maker,
      to which such sale or transfer was made or a party to such share exchange,
      as
      the case may be (“ constituent
      person ”),
      or an
      affiliate of a constituent person and (ii) failed to exercise his rights of
      election, if any, as to the kind or amount of securities, cash and other
      property receivable upon such reclassification, consolidation, merger, sale,
      transfer or share exchange (provided that if the kind or amount of securities,
      cash and other property receivable upon such reclassification, consolidation,
      merger, sale, transfer or share exchange is not the same for each share of
      Common Stock of Maker held immediately prior to such consolidation, merger,
      sale
      or transfer by other than a constituent person or an affiliate thereof and
      in
      respect of which such rights of election shall not have been exercised
      (“ non-electing
      share ”),
      then
      the kind and amount of securities, cash and other property receivable upon
      such
      reclassification, consolidation, merger, sale, transfer or share exchange by
      each non-electing share shall be deemed to be the kind and amount so receivable
      per share by a plurality of the non-electing shares). Maker, the person formed
      by such consolidation or resulting from such merger or which acquires such
      assets or which acquires Maker’s shares, as the case may be, shall make
      provisions in its certificate or articles of incorporation or other constituent
      document to establish such right. Such certificate or articles of incorporation
      or other constituent document shall provide for adjustments which, for events
      subsequent to the effective date of such certificate or articles of
      incorporation or other constituent document, shall be as nearly equivalent
      as
      may be practicable to the adjustments provided for herein. The above provisions
      shall similarly apply to successive reclassifications, consolidations, mergers,
      sales, transfers or share exchanges.





(g)  *Reservation
      of Shares; Transfer Taxes; Etc.* Maker
      shall at all times reserve and keep available, out of its authorized and
      unissued stock, solely for the purpose of effecting the conversion of this
      Note,
      such number of shares of its Common Stock and other securities free of
      preemptive rights as shall from time to time be sufficient to effect the
      conversion of this Note. Maker shall from time to time, in accordance with
      the
      laws of the State of Delaware, increase the authorized number of shares of
      Common Stock if at any time the number of shares of Common Stock not outstanding
      shall not be sufficient to permit the conversion of this Note. If the Common
      Stock is listed on the New York Stock Exchange, the Nasdaq National Market,
      or
      any other national securities exchange, Maker will, if permitted by the rules
      of
      such exchange, list and keep listed on such exchange, upon official notice
      of
      issuance, all shares of Common Stock issuable upon conversion of this Note.
      Maker shall pay any and all issue or other taxes that may be payable in respect
      of any issue or delivery of shares of Common Stock or other securities upon
      conversion of this Note by Payee.


-4-


5.  Defined
      Terms .
      As used
      in this Note, the following terms have the respective meanings set forth
      below:





(a)  “ Common
      Stock ”
shall
      mean the common stock of Maker, par value $0.001, and any capital stock into
      which such common stock shall have been changed and any other stock resulting
      from any reclassification of such stock which is not preferred as to dividends
      or assets over any other class of stock which shall be in effect from time
      to
      time.





(b)  “ Conversion
      Price ”
shall
      mean, subject to adjustment as provided in Section 4(d) hereof,





i.
            the
                average of the last reported sale prices on the principal trading
                market
                for the Common Stock for the ten (10) trading days immediately preceding
                the date of delivery of the applicable Optional Conversion Notice
                or
                Mandatory Conversion Notice, or





ii.
            if
                the Conversion Price cannot be calculated as of such date on the
                foregoing
                basis, the fair market value of one share of Common Stock as reasonably
                determined in good faith by the Board of Directors of the
                Company;





**[provided,
      however, that in the event of an Optional Conversion of all or part of this
      Note, such Conversion Price shall not be less than $0.50 nor greater than $1.00,
      and in the event of a Mandatory Conversion, such Conversion Price shall be
      $1.20.]**





The
      manner of determining the Conversion Price of the Common Stock set forth in
      the
      foregoing definition shall apply with respect to any other security in respect
      of which a determination as to Conversion Price must be made
      hereunder.





6.  No
      Impairment .
      Maker
      will not, by amendment of its certificate or articles of incorporation or
      through any reorganization, transfer of assets, merger, dissolution, issuance
      or
      sale of securities or any other voluntary action or inaction, intentionally
      avoid or seek to avoid the observance or performance of any of the material
      terms to be observed or performed hereunder by Maker but will at all times
      in
      good faith assist in the carrying out of all the provisions of this
      Note.





7.  Cumulative
      Rights .
      No
      delay on the part of the holder of this Note in the exercise of any power or
      right under this Note, or under any document or instrument executed in
      connection herewith, shall operate as a waiver thereof, nor shall a single
      or
      partial exercise of any other power or right.





8.  Waiver .
      Maker,
      and each surety, endorser, guarantor, and other party ever liable for the
      payment of any sum of money payable on this Note, jointly and severally waive
      demand, presentment, protest, notice of nonpayment, notice of intention to
      accelerate, notice of acceleration, notice of protest, and any and all lack
      of
      diligence or delay in collection or the filing of suit hereon which may occur;
      agree that their liability on this Note shall not be affected by any renewal
      or
      extension in the time of payment hereof, by any indulgences, or by any release
      or change in any security for the payment of this Note; and hereby consent
      to
      any and all renewals, extensions, indulgences, releases, or changes hereof
      or
      hereto, regardless of the number of such renewals, extensions, indulgences,
      releases, or changes.


-5-


9.  Attorneys’
      Fees and Costs .
      In the
      event that this Note is placed in the hands of attorneys 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, incurred
      by the holder hereof on account of such collection.





10.  NO
      ORAL AGREEMENTS .
      THIS
      NOTE (ALONG WITH THE OTHER DOCUMENTS AND INSTRUMENTS EXECUTED AND DELIVERED
      PURSUANT THERETO) REPRESENTS THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY
      NOT
      BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL
      AGREEMENTS OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE
      PARTIES.





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





12.  Severability .
      If any
      provision of this Note shall be held to be unenforceable by a court of competent
      jurisdiction, such provisions shall be severed from this Note and the remainder
      of this Note shall continue in full force and effect.





13.  Assignment .
      This
      Note, or any portion hereof, may be assigned by Payee without the consent of
      Maker. Any such assignment by Payee shall be in compliance with the Securities
      Act and applicable state securities laws.





14.  Notice .
      All
      notices, requests and demands to or upon the respective parties hereto to be
      effective shall be in writing (including by facsimile and electronic
      transmission) and, unless otherwise expressly provided herein, shall be deemed
      to have been duly given or made (i) in the case of delivery by hand, when
      delivered, (ii) in the case of delivery by mail, three (3) days after being
      deposited in the mails, postage prepaid, or (iii) in the case of delivery by
      facsimile or electronic transmission, when sent and receipt has been confirmed,
      addressed as follows:





If
                to Maker:
            Gabriel
                Technologies Corporation


4538
      South 140 th Street


Omaha,
      NE
      68137


Facsimile:
      ________________








Attention:
            President





If
      to
      Payee:


CTSL
      Investment, LLC


675
      South
      Fork Drive


Des
      Moines, Iowa 50263


Facsimile:
      ____________________


Attention:
      ____________________


-6-


15.  Limitation
      on Interest .
      It is
      the intent of Payee and Maker in the execution of this Note and all other
      instruments now or hereafter securing this Note to contract in strict compliance
      with applicable usury law. In furtherance thereof, Payee and Maker stipulate
      and
      agree that none of the terms and provisions contained in this Note, or in any
      other instrument executed in connection herewith, shall ever be construed to
      create a contract to pay for the use, forbearance or detention of money,
      interest at a rate in excess of the maximum interest rate permitted to be
      charged by applicable law; that neither Maker nor any guarantors, endorsers
      or
      other parties now or hereafter becoming liable for payment of this Note shall
      ever be obligated or required to pay interest on this Note at a rate in excess
      of the maximum interest that may be lawfully charged under applicable law;
      and
      that the provisions of this paragraph shall control over all other provisions
      of
      this Note and any other instruments now or hereafter executed in connection
      herewith which may be in apparent conflict herewith. The holder of this Note
      expressly disavows any intention to charge or collect excessive unearned
      interest or finance charges in the event the maturity of this Note is
      accelerated. If the interest received for the actual period of existence of
      the
      loan evidenced by this Note exceeds the applicable maximum lawful rate, the
      holder of this Note shall, at its option, either refund to Maker the amount
      of
      such excess or credit the amount of such excess against the principal balance
      of
      this Note then outstanding and thereby shall render inapplicable any and all
      penalties of any kind provided by applicable law as a result of such excess
      interest. In the event that Payee or any other holder of this Note shall
      contract for, charge or receive any amount or amounts and/or any other thing
      of
      value which are determined to constitute interest which would increase the
      effective interest rate on this Note to a rate in excess of that permitted
      to be
      charged by applicable law, an amount equal to interest in excess of the lawful
      rate shall, upon such determination, at the option of the holder of this Note,
      be either immediately returned to Maker or credited against the principal
      balance of this Note then outstanding, in which event any and all penalties
      of
      any kind under applicable law as a result of such excess interest shall be
      inapplicable. The term “applicable law” as used in this Note shall mean the laws
      of the State of Delaware or the laws of the United States, whichever laws allow
      the greater rate of interest, as such laws now exist or may be changed or
      amended or come into effect in the future.





IN
      WITNESS WHEREOF, the undersigned has executed this Note as of the day and year
      first above written.








MAKER:





**GABRIEL
      TECHNOLOGIES** **CORPORATION**











By:  /s/
      Keith R.
      Feilmeier


Name:
      ___________________________________


Title:  President