Exhibit
      4.1

    


    THESE
      SECURITIES AND THE UNDERLYING SHARES OF COMMON STOCK HAVE NOT BEEN REGISTERED
      WITH THE SECURITIES AND EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF
      ANY
      STATE IN RELIANCE UPON AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES
      ACT
      OF 1933, AS AMENDED (THE “SECURITIES ACT”), AND, ACCORDINGLY, MAY NOT BE OFFERED
      OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE
      SECURITIES ACT OR PURSUANT TO AN AVAILABLE EXEMPTION FROM, OR IN A TRANSACTION
      NOT SUBJECT TO, THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT AND IN
      ACCORDANCE WITH APPLICABLE STATE SECURITIES LAWS AS EVIDENCED BY A LEGAL OPINION
      OF COUNSEL TO THE TRANSFEROR TO SUCH EFFECT, THE SUBSTANCE OF WHICH SHALL BE
      REASONABLY ACCEPTABLE TO THE COMPANY. THESE SECURITIES MAY BE PLEDGED IN
      CONNECTION WITH A BONA FIDE MARGIN ACCOUNT WITH A REGISTERED BROKER-DEALER
      OR
      OTHER LOAN WITH A FINANCIAL INSTITUTION THAT IS AN “ACCREDITED INVESTOR” AS
      DEFINED IN RULE 501(a) UNDER THE SECURITIES ACT.

     

    FORM
      OF COMMON STOCK PURCHASE WARRANT

     

    To
      Purchase [Number
      of Shares Underlying Warrant] Shares
      of
      Common Stock of

     

    SRKP
      21, Inc.

     

    THIS
      COMMON STOCK PURCHASE WARRANT CERTIFIES that, for value received, [Name
      of Investor]
      (the
“Holder”),
      is
      entitled, upon the terms and subject to the limitations on exercise and the
      conditions hereinafter set forth, at any time on or after the date hereof (the
      “Initial
      Exercise Date”)
      and on
      or prior to the close of business on the earlier of (i) ten years from the
      Initial Exercise Date or (ii) five years from the date the Company (as defined
      below) consummates a merger or other business combination with an operating
      business or any other event pursuant to which the Company ceases to be a “shell
      company,” as defined by Rule 12b-2 under the Securities Exchange Act of 1934 and
      a “blank check company,” as defined by Rule 419 of the Securities Act (the
“Termination
      Date”)
      but
      not thereafter, to subscribe for and purchase from SRKP 21, Inc., a Delaware
      corporation (the “Company”),
      up to
[Number
      of Shares Underlying Warrant] shares
      (the “Warrant
      Shares”)
      of the
      Company’s common stock, par value $.0001 per share (the “Common
      Stock”).
      The
      purchase price of one share of Common Stock (the “Exercise
      Price”)
      under
      this Warrant shall be $.0001,
      subject
      to adjustment hereunder. The Exercise Price and the number of Warrant Shares
      for
      which the Warrant is exercisable shall be subject to adjustment as provided
      herein.

     

    1.
      Title
      to Warrant. Prior to the Termination Date and subject to compliance with
      applicable laws and Section 7 of this Warrant, this Warrant and all rights
      hereunder are transferable, in whole or in part, at the office or agency of
      the
      Company by the Holder in person or by duly authorized attorney, upon surrender
      of this Warrant together with the Assignment Form annexed hereto properly
      endorsed. The transferee shall sign an investment letter in form and substance
      reasonably satisfactory to the Company.

     

    2.
      Authorization of Shares. The Company covenants that all Warrant Shares
      which may be issued upon the exercise of the purchase rights represented by
      this
      Warrant will, upon exercise of the purchase rights represented by this Warrant,
      be duly authorized, validly issued, fully paid and nonassessable and free from
      all taxes, liens and charges in respect of the issue thereof (other than taxes
      in respect of any transfer occurring contemporaneously with such
      issue).

     

    
      
        
          
          

        

        
          
          

          
            

          

        

        
          
          

        

      

    

    


    3.
      Exercise of Warrant.

     

    (a) Except
      as
      provided in Section 4 herein, exercise of the purchase rights represented by
      this Warrant may be made at any time or times on or after the Initial Exercise
      Date and on or before the Termination Date by the surrender of this Warrant
      and
      the Notice of Exercise Form annexed hereto duly executed, at the office of
      the
      Company (or such other office or agency of the Company as it may designate
      by
      notice in writing to the registered Holder at the address of such Holder
      appearing on the books of the Company). Upon payment of the Exercise Price
      of
      the shares thereby purchased by wire transfer or cashier’s check drawn on a
      United States bank, the Holder shall be entitled to receive a certificate for
      the number of Warrant Shares so purchased. Certificates for Warrant Shares
      purchased hereunder shall be delivered to the Holder within five (5) business
      days after the date on which this Warrant shall have been exercised as
      aforesaid. This Warrant shall be deemed to have been exercised and such
      certificate or certificates shall be deemed to have been issued, and Holder
      or
      any other person so designated to be named therein shall be deemed to have
      become a holder of record of such Warrant Shares for all purposes, as of the
      date the Warrant has been exercised by payment to the Company of the Exercise
      Price and all taxes required to be paid by the Holder, if any, pursuant to
      Section 5 prior to the issuance of such shares, have been paid. If the Company
      fails to deliver to the Holder a certificate or certificates representing the
      Warrant Shares pursuant to this Section 3(a) by the fifth business day after
      the
      date of exercise, then the Holder will have the right to rescind such exercise
      by written notice to the Company.


     

    (b) If
      this
      Warrant shall have been exercised in part, the Company shall, at the time of
      delivery of the certificate or certificates representing Warrant Shares, deliver
      to Holder a new Warrant evidencing the rights of Holder to purchase the
      unpurchased Warrant Shares called for by this Warrant, which new Warrant shall
      in all other respects be identical with this Warrant. 

    


    (c)
       This
      Warrant may also be exercised, in whole or in part, at any time prior to the
      Termination Date, by means of a “cashless exercise” in which the Holder shall be
      entitled to receive a certificate for the number of Warrant Shares equal to
      the
      quotient obtained by dividing [(A-B) (X)] by (A), where:


    (A)
      = the
      closing bid price on the trading day preceding the date of such
      election;

    


    (B)
      = the
      Exercise Price of the Warrants, as adjusted; and 

    


    (X)
      = the
      number of Warrant Shares issuable upon exercise of the Warrants in accordance
      with the terms of this Warrant.

    


    4.
      No
      Fractional Shares or Scrip. No fractional shares or scrip representing
      fractional shares shall be issued upon the exercise of this Warrant. As to
      any
      fraction of a share which Holder would otherwise be entitled to purchase upon
      such exercise, the Company shall pay a cash adjustment in respect of such final
      fraction in an amount equal to such fraction multiplied by the Exercise
      Price.

     

    5.
      Charges, Taxes and Expenses. Issuance of certificates for Warrant Shares
      shall be made without charge to the Holder for any issue or transfer tax or
      other incidental expense in respect of the issuance of such certificate, all
      of
      which taxes and expenses shall be paid by the Company, and such certificates
      shall be issued in the name of the Holder or in such name or names as may be
      directed by the Holder; provided, however, that in the event certificates for
      Warrant Shares are to be issued in a name other than the name of the Holder,
      this Warrant when surrendered for exercise shall be accompanied by the
      Assignment Form attached hereto duly executed by the Holder; and the Company
      may
      require, as a condition thereto, the payment of a sum sufficient to reimburse
      it
      for any transfer tax incidental thereto.

     

    
      
        
          
          

        

        
          
          

          
            

          

        

        
          
          

        

      

    

    


    6.
      Closing of Books. The Company will not close its stockholder books or
      records in any manner which prevents the timely exercise of this Warrant,
      pursuant to the terms hereof.

     

    7.
      Transfer, Division and Combination. 

     

    (a) Subject
      to compliance with any applicable securities laws and the conditions set forth
      in Sections 1 and 7(e) hereof, this Warrant and all rights hereunder are
      transferable, in whole or in part, upon surrender of this Warrant at the
      principal office of the Company, together with a written assignment of this
      Warrant substantially in the form attached hereto duly executed by the Holder
      or
      its agent or attorney and funds sufficient to pay any transfer taxes payable
      upon the making of such transfer. Upon such surrender and, if required, such
      payment, the Company shall execute and deliver a new Warrant or Warrants in
      the
      name of the assignee or assignees and in the denomination or denominations
      specified in such instrument of assignment, and shall issue to the assignor
      a
      new Warrant evidencing the portion of this Warrant not so assigned, and this
      Warrant shall promptly be cancelled. A Warrant, if properly assigned, may be
      exercised by a new holder for the purchase of Warrant Shares without having
      a
      new Warrant issued.

    


    (b) This
      Warrant may be divided or combined with other Warrants upon presentation hereof
      at the aforesaid office of the Company, together with a written notice
      specifying the names and denominations in which new Warrants are to be issued,
      signed by the Holder or its agent or attorney. Subject to compliance with
      Section 7(a), as to any transfer which may be involved in such division or
      combination, the Company shall execute and deliver a new Warrant or Warrants
      in
      exchange for the Warrant or Warrants to be divided or combined in accordance
      with such notice.

    


    (c) The
      Company shall prepare, issue and deliver at its own expense (other than transfer
      taxes) the new Warrant or Warrants under this Section 7.

    


    (d) The
      Company agrees to maintain, at its aforesaid office, books for the registration
      and the registration of transfer of the Warrants.

    


    (e) If,
      at the
time
      of
      the surrender of this Warrant in connection with any transfer of this Warrant,
      the transfer of this Warrant shall not be registered pursuant to an effective
      registration
      statement under the Securities Act
      and
under
      applicable state securities or blue sky laws, the Company may require, as a
      condition of allowing such transfer, (i) that the Holder or transferee of this
      Warrant, as the case may be, furnish to the Company a written opinion of counsel
      reasonably acceptable to the Company (which opinion shall be in form, substance
      and scope customary for opinions of counsel in comparable transactions) to
      the
      effect that such transfer may be made without
      registration under the
      Securities Act and under applicable state securities or blue sky laws and (ii)
      that the holder or transferee execute and deliver to the Company an investment
      letter in form and substance acceptable to the Company.


    
      
        
        

      

      
        
        

        
          

        

      

      
        
        

      

    


    8.
      No
      Rights as Shareholder until Exercise.
      This
      Warrant does not entitle the Holder to any voting rights or other rights as
      a
      shareholder of the Company prior to the exercise hereof. Upon the surrender
      of
      this Warrant and the payment of the aggregate Exercise Price, the Warrant Shares
      so purchased shall be and be deemed to be issued to such Holder as the record
      owner of such shares as of the close of business on the later of the date of
      such surrender or payment. 

     

    9.
      Loss,
      Theft, Destruction or Mutilation of Warrant. The Company covenants that upon
      receipt by the Company of evidence reasonably satisfactory to it of the loss,
      theft, destruction or mutilation of this Warrant or any stock certificate
      relating to the Warrant Shares, and in case of loss, theft or destruction,
      of
      indemnity or security reasonably satisfactory to it (which, in the case of
      the
      Warrant, shall not include the posting of any bond), and upon surrender and
      cancellation of such Warrant or stock certificate, if mutilated, the Company
      will make and deliver a new Warrant or stock certificate of like tenor and
      dated
      as of such cancellation, in lieu of such Warrant or stock
      certificate.

     

    10.
      Saturdays, Sundays, Holidays, etc. If the last or appointed day for the
      taking of any action or the expiration of any right required or granted herein
      shall be a Saturday, Sunday or a legal holiday, then such action may be taken
      or
      such right may be exercised on the next succeeding day not a Saturday, Sunday
      or
      legal holiday.

     

    11.
      Adjustments of Exercise Price and Number of Warrant Shares. The number
      and kind of securities purchasable upon the exercise of this Warrant and the
      Exercise Price shall be subject to adjustment from time to time upon the
      happening of any of the following. In case the Company shall (i) pay a dividend
      in shares of Common Stock or make a distribution in shares of Common Stock
      to
      holders of its outstanding Common Stock, (ii) subdivide its outstanding shares
      of Common Stock into a greater number of shares, (iii) combine its outstanding
      shares of Common Stock into a smaller number of shares of Common Stock, or
      (iv)
      issue any shares of its capital stock in a reclassification of the Common Stock,
      then in each such case the number of Warrant Shares purchasable upon exercise
      of
      this Warrant immediately prior thereto shall be adjusted so that the Holder
      shall be entitled to receive the kind and number of Warrant Shares or other
      securities of the Company which it would have owned or have been entitled to
      receive had such Warrant been exercised in advance thereof. Upon
      each
      such adjustment of the kind and number of Warrant Shares or other securities
      of
      the Company which are purchasable hereunder, the Holder shall thereafter be
      entitled to purchase the number of Warrant Shares or other securities resulting
      from such adjustment at an Exercise Price per Warrant Share or other security
      obtained by multiplying the Exercise Price in effect immediately prior to such
      adjustment by the number of Warrant Shares purchasable pursuant hereto
      immediately prior to such adjustment and dividing by the number of Warrant
      Shares or other securities of the Company resulting from such adjustment.
An
      adjustment made pursuant to this paragraph shall become effective immediately
      after the effective date of such event retroactive to the record date, if any,
      for such event.

     

    12.
      Reorganization, Reclassification, Merger, Consolidation or Disposition
      of
      Assets. In case the Company shall reorganize its capital, reclassify its
      capital stock, consolidate or merge with or into another corporation (where
      the
      Company is not the surviving corporation or where there is a change in or
      distribution with respect to the Common Stock of the Company), or sell, transfer
      or otherwise dispose of all or substantially all its property, assets or
      business to another corporation and, pursuant to the terms of such
      reorganization, reclassification, merger, consolidation or disposition of
      assets, shares of common stock of the successor or acquiring corporation, or
      any
      cash, shares of stock or other securities or property of any nature whatsoever
      (including warrants or other subscription or purchase rights) in addition to
      or
      in lieu of common stock of the successor or acquiring corporation (“Other
      Property”), are to be received by or distributed to the holders of Common Stock
      of the Company, then the Holder shall have the right thereafter to receive,
      at
      the option of the Holder, upon exercise of this Warrant, the number of shares
      of
      Common Stock of the successor or acquiring corporation or of the Company, if
      it
      is the surviving corporation, and Other Property receivable upon or as a result
      of such reorganization, reclassification, merger, consolidation or disposition
      of assets by a Holder of the number of shares of Common Stock for which this
      Warrant is exercisable immediately prior to such event. In case of any such
      reorganization, reclassification, merger, consolidation or disposition of
      assets, the successor or acquiring corporation (if other than the Company)
      shall
      expressly assume the due and punctual observance and performance of each and
      every covenant and condition of this Warrant to be performed and observed by
      the
      Company and all the obligations and liabilities hereunder, subject to such
      modifications as may be deemed appropriate (as determined in good faith by
      resolution of the Board of Directors of the Company) in order to provide for
      adjustments of Warrant Shares for which this Warrant is exercisable which shall
      be as nearly equivalent as practicable to the adjustments provided for in this
      Section 12. For purposes of this Section 12, “common stock of the successor or
      acquiring corporation” shall include stock of such corporation of any class
      which is not preferred as to dividends or assets over any other class of stock
      of such corporation and which is not subject to redemption and shall also
      include any evidences of indebtedness, shares of stock or other securities
      which
      are convertible into or exchangeable for any such stock, either immediately
      or
      upon the arrival of a specified date or the happening of a specified event
      and
      any warrants or other rights to subscribe for or purchase any such stock. The
      foregoing provisions of this Section 12 shall similarly apply to successive
      reorganizations, reclassifications, mergers, consolidations or disposition
      of
      assets. 

     

    
      
        
        

      

      
        
        

        
          

        

      

      
        
        

      

    


    13.
      Voluntary Adjustment by the Company. The Company may at any time during
      the term of this Warrant reduce the then current Exercise Price to any amount
      and for any period of time deemed appropriate by the Board of Directors of
      the
      Company.

     

    14.
      Notice of Adjustment. Whenever the number of Warrant Shares or number or
      kind of securities or other property purchasable upon the exercise of this
      Warrant or the Exercise Price is adjusted, as herein provided, the Company
      shall
      give notice thereof to the Holder, which notice shall state the number of
      Warrant Shares (and other securities or property) purchasable upon the exercise
      of this Warrant and the Exercise Price of such Warrant Shares (and other
      securities or property) after such adjustment, setting forth a brief statement
      of the facts requiring such adjustment and setting forth the computation by
      which such adjustment was made.

     

    15.
      Notice of Corporate Action. If at any time:

     

    (a) the
      Company shall take a record of the holders of its Common Stock for the purpose
      of entitling them to receive a dividend or other distribution, or any right
      to
      subscribe for or purchase any evidences of its indebtedness, any shares of
      stock
      of any class or any other securities or property, or to receive any other right,
      or

    


    (b) there
      shall be any capital reorganization of the Company, any reclassification or
      recapitalization of the capital stock of the Company or any consolidation or
      merger of the Company with, or any sale, transfer or other disposition of all
      or
      substantially all the property, assets or business of the Company to, another
      corporation or,

    


    (c) there
      shall be a voluntary or involuntary dissolution, liquidation or winding up
      of
      the Company;

    


    then,
      in
      any one or more of such cases (but not in such cases if the rights of the Holder
      or holders of Common Stock will not be materially affected thereby, as for
      example in the case of a merger to effect a change of domicile), the Company
      shall give to Holder (i) at least 5 business days’ prior notice of the date on
      which a record date shall be selected for such dividend, distribution or right
      or for determining rights to vote in respect of any such reorganization,
      reclassification, merger, consolidation, sale, transfer, disposition,
      liquidation or winding up, and (ii) in the case of any such reorganization,
      reclassification, merger, consolidation, sale, transfer, disposition,
      dissolution, liquidation or winding up, at least 5 business days’ prior notice
      of the date when the same shall take place. Such notice in accordance with
      the
      foregoing clause also shall specify (i) the date on which any such record is
      to
      be taken for the purpose of such dividend, distribution or right, the date
      on
      which the holders of Common Stock shall be entitled to any such dividend,
      distribution or right, and the amount and character thereof, and (ii) the date
      on which any such reorganization, reclassification, merger, consolidation,
      sale,
      transfer, disposition, dissolution, liquidation or winding up is to take place
      and the time, if any such time is to be fixed, as of which the holders of Common
      Stock shall be entitled to exchange their Warrant Shares for securities or
      other
      property deliverable upon such disposition, dissolution, liquidation or winding
      up. Each such written notice shall be sufficiently given if addressed to Holder
      at the last address of Holder appearing on the books of the Company and
      delivered in accordance with Section 18(d).


    
      
        
        

      

      
        
        

        
          

        

      

      
        
        

      

    


    16.
      Authorized Shares. The Company covenants that during the period the
      Warrant is outstanding, it will reserve from its authorized and unissued Common
      Stock a sufficient number of shares to provide for the issuance of the Warrant
      Shares upon the exercise of any purchase rights under this Warrant. The Company
      further covenants that its issuance of this Warrant shall constitute full
      authority to its officers who are charged with the duty of executing stock
      certificates to execute and issue the necessary certificates for the Warrant
      Shares upon the exercise of the purchase rights under this Warrant. The Company
      will take all such reasonable action as may be necessary to assure that such
      Warrant Shares may be issued as provided herein without violation of any
      applicable law or regulation, or of any requirements of the trading market
      upon
      which the Common Stock may be listed. 

     

    Except
      and to the extent as waived or consented to by the Holder, the Company shall
      not
      by any action, including, without limitation, amending its certificate of
      incorporation or through any reorganization, transfer of assets, consolidation,
      merger, dissolution, issue or sale of securities or any other voluntary action,
      avoid or seek to avoid the observance or performance of any of the terms of
      this
      Warrant, but will at all times in good faith assist in the carrying out of
      all
      such terms and in the taking of all such actions as may be necessary or
      appropriate to protect the rights of Holder as set forth in this Warrant against
      impairment. Without limiting the generality of the foregoing, the Company will
      (a) not increase the par value of any Warrant Shares above the amount payable
      therefor upon such exercise immediately prior to such increase in par value,
      (b)
      take all such action as may be necessary or appropriate in order that the
      Company may validly and legally issue fully paid and nonassessable Warrant
      Shares upon the exercise of this Warrant, and (c) use commercially reasonable
      efforts to obtain all such authorizations, exemptions or consents from any
      public regulatory body having jurisdiction thereof as may be necessary to enable
      the Company to perform its obligations under this Warrant.

    


    Before
      taking any action which would result in an adjustment in the number of Warrant
      Shares for which this Warrant is exercisable or in the Exercise Price, the
      Company shall obtain all such authorizations or exemptions thereof, or consents
      thereto, as may be necessary from any public regulatory body or bodies having
      jurisdiction thereof.

    


    17. Miscellaneous.

    


    (a)
      Jurisdiction.
      This
      Warrant shall constitute a contract under the laws of Delaware, without regard
      to its conflicts of laws principles or rules.

     

    (b)
      Restrictions.
      The
      Holder acknowledges that the Warrant Shares acquired upon the exercise of this
      Warrant, if not registered, will have restrictions upon resale imposed by state
      and federal securities laws.

     

    (c)
      Nonwaiver
      and Expenses.
      No
      course of dealing or any delay or failure to exercise any right hereunder on
      the
      part of Holder shall operate as a waiver of such right or otherwise prejudice
      Holder’s rights, powers or remedies, notwithstanding all rights hereunder
      terminate on the Termination Date. If the Company willfully and knowingly fails
      to comply with any provision of this Warrant, which results in any material
      damages to the Holder, the Company shall pay to Holder such amounts as shall
      be
      sufficient to cover any costs and expenses including, but not limited to,
      reasonable attorneys’ fees, including those of appellate proceedings, incurred
      by Holder in collecting any amounts due pursuant hereto or in otherwise
      enforcing any of its rights, powers or remedies hereunder.

     


    
      
        
        

      

      
        
        

        
          

        

      

      
        
        

      

    


    (d)
      Notices.
      Any
      notice, request or other document required or permitted to be given or delivered
      pursuant to this Warrant shall
      be
      deemed to have been sufficiently given and received for all purposes when
      delivered by hand or by telecopy that has been confirmed as received by 5:00
      P.M. on a business day, one (1) business day after being sent by nationally
      recognized overnight courier or received by telecopy after 5:00 P.M. on any
      day,
      or five (5) business days after being sent by certified or registered mail,
      postage and charges prepaid, return receipt requested, to the following
      addresses:

     

    
      	
              If
                to the Company:

            	
              SRKP
                21, Inc.

            
	 	
              4737
                North Ocean Drive, Suite 207

            
	 	
              Lauderdale
                by the Sea, FL 33308

            
	 	
              Attn:
                Anthony C. Pintsopoulos, CFO

            


    

     

    If
      to the
      Holder: At
      the
      Holder’s address in the Company’s Warrant register.

    


    (e)
      Limitation
      of Liability.
      No
      provision hereof, in the absence of any affirmative action by Holder to exercise
      this Warrant or purchase Warrant Shares, and no enumeration herein of the rights
      or privileges of Holder, shall give rise to any liability of Holder for the
      purchase price of any Common Stock or as a stockholder of the Company, whether
      such liability is asserted by the Company or by creditors of the
      Company.

     

    (f)
      Remedies.
      Holder,
      in addition to being entitled to exercise all rights granted by law, including
      recovery of damages, will be entitled to specific performance of its rights
      under this Warrant. The Company agrees that monetary damages would not be
      adequate compensation for any loss incurred by reason of a breach by it of
      the
      provisions of this Warrant and hereby agrees to waive the defense in any action
      for specific performance that a remedy at law would be adequate.

     

    (g)
      Successors
      and Assigns.
      Subject
      to applicable securities laws, this Warrant and the rights and obligations
      evidenced hereby shall inure to the benefit of and be binding upon the
      successors of the Company and the successors and permitted assigns of Holder.
      The provisions of this Warrant are intended to be for the benefit of all Holders
      from time to time of this Warrant and shall be enforceable by any such Holder
      or
      holder of Warrant Shares.

     

    (h)
      Amendment.
      This
      Warrant may be modified or amended or the provisions hereof waived with the
      written consent of the Holder and the Company. 

     

    (i)
      Severability.
      Wherever possible, each provision of this Warrant shall be interpreted in such
      manner as to be effective and valid under applicable law, but if any provision
      of this Warrant shall be prohibited by or invalid under applicable law, such
      provision shall be ineffective to the extent of such prohibition or invalidity,
      without invalidating the remainder of such provisions or the remaining
      provisions of this Warrant.

     


    
      
        
        

      

      
        
        

        
          

        

      

      
        
        

      

    


    (j)
      Headings.
      The
      headings used in this Warrant are for the convenience of reference only and
      shall not, for any purpose, be deemed a part of this Warrant.

     

    IN
      WITNESS WHEREOF, the Company has caused this Warrant to be executed by its
      officer thereunto duly authorized.

     

    Dated:
      October 11, 2007

    


    
      	SRKP
              21, INC.
	 	 
	
              By:

            	
              /s/
                Richard A. Rappaport

            
	 	
              Name:
                Richard A. Rappaport

            
	 	
              Title:
                President

            


    


    
      
        
        

      

      
        
        

        
          

        

      

      
        
        

      

    


    NOTICE
      OF EXERCISE

    


    To:       SRKP
      21,
      Inc.

    


    (1) The
      undersigned hereby elects to purchase ________ Warrant Shares of SRKP 21, Inc.
      pursuant to the terms of the attached Warrant, and tenders herewith payment
      of
      the exercise price in full, together with all applicable transfer taxes, if
      any.

     

    (2) Please
      issue a certificate or certificates representing said Warrant Shares in the
      name
      of the undersigned or in such other name as is specified below:

     

    
      	
              Name:
                

            	 
	 	 
	
              Address:

            	 
	 	 
	 	 
	 	 
	
              SS:

            	 


    

    


    The
      Warrant Shares shall be delivered to the following:

    


    
      	 
	 
	 
	 
	 


    

     

    


    
      	
              By:
                

            	 
	 	
                  
                [Name of Investor]

            
	 	 
	
              Dated:
                

            	 


    


    
      
        
        

      

      
        
        

        
          

        

      

      
        
        

      

    

     

    ASSIGNMENT
      FORM

    


    (To
      assign the foregoing warrant, execute

    this
      form
      and supply required information. 

    Do
      not
      use this form to exercise the warrant.)

    


    FOR
      VALUE
      RECEIVED, the foregoing Warrant and all rights evidenced thereby are hereby
      assigned to _______________________________________________
      whose address is

    


    _______________________________________________________________.

     

    _______________________________________________________________

    


    Dated:
      ______________, _______

    


    


    
      	
              Holder's
                Signature:

            	
               

            
	 	 
	
              Holder's
                Address:

            	
               

            
	 	 
	 	 


    

    


    
      	
              Signature Guaranteed:
                

            	 


    

     

    NOTE:
      The
      signature to this Assignment Form must correspond with the name as it appears
      on
      the face of the Warrant, without alteration or enlargement or any change
      whatsoever, and must be guaranteed by a bank or trust company. Officers of
      corporations and those acting in a fiduciary or other representative capacity
      should file proper evidence of authority to assign the foregoing
      Warrant.