EXHIBIT
      4.2

    


    LETTER
      OF ESCROW INSTRUCTIONS

    


    


    
      	To:	
              Wells
                Fargo Bank, N.A.

            


    

    Corporate
      Trust and Escrow Services

    201
      Main
      Street, Suite 301

    Fort
      Worth, Texas 76102

    Attention:
      John Stohlmann

    


    
      	 	
              Stirling
                Acquisition Corporation - Rule 419
                escrow,

            


    


Wells
  Fargo Bank Escrow No. 22457100

     

    This
      Letter of Escrow Instructions to Wells Fargo Bank, N.A., which is referred
      to as
“Escrow Agent,” shall immediately and automatically become operative and
      effective upon the commencement of a public distribution of common stock by
      Stirling Acquisition Corporation, which is referred to as the “Company,” as more
      fully described in the prospectus that forms a part of the Company’s Form S-1
      Registration Statement under the Securities Act of 1933 (Registration No.
      333-142921) which is referred to as the “Registration Statement.”

     

    The
      Company will deliver the documents, papers, stock transfer records and other
      property hereinafter described to the Escrow Agent. All such documents, papers,
      stock transfer records and other property are to be held and disposed of by
      the
      Escrow Agent in accordance with the following instructions and upon the terms
      and conditions hereinafter set forth, to which the undersigned
      agree:

     

    
      	1.	
              ESCROW
                PURPOSE:

            


    

     

    
      	
              1.1

            	
              This
                Escrow Agreement describes clearing and holding escrow that will
                be
                established by Stirling Acquisition Corporation, of Dunedin, Florida,
                (the
                “Company”) and all current stockholders of the Company (the “Founders”) in
                accordance with the requirements of Securities and Exchange Commission
                Rule 419, adopted pursuant to the provisions of Section 7(b) of the
                Securities Act of 1933. The Company, the Founders and the Escrow
                Agent are
                the only parties to this Agreement.

            


    

     

    
      	
              1.2

            	
              In
                connection with the distribution described in the Registration Statement
                (the “Distribution”), the Founders intend to transfer certain shares of
                the Company’s $.001 par value common stock (the “Common Stock”) to various
                classes of transferees as more fully described in the definitive
                prospectus that will be issued upon receipt of an order of effectiveness
                for the Registration Statement (the
                “Prospectus).

            


    

     

    
      	
              1.3

            	
              The
                purpose of the escrow shall be to hold and ultimately distribute
                up to
                250,000 shares of Common Stock (the “Gift Shares” or “Escrowed Assets”) to
                various individuals and organizations selected by them in accordance
                with
                the terms of Sections 4 through 6 this Escrow
                Agreement.

            


    

     

    
      	
              1.4

            	
              This
                Escrow Agreement constitutes an essential element of the Company’s
                proposed public offering of securities and is required by Securities
                and
                Exchange Commission Rule 419. The Company and the Founders shall, at
                all times, conduct all of their activities relating to the Rule 419
                escrow created hereby in strict compliance with the letter and the
                spirit
                of Rule 419. In the event of any inconsistency between the terms of
                this Escrow Agreement and the requirements of Rule 419, the
                requirements of Rule 419 shall have priority. The Escrow Agent shall
                have no duty to monitor or ensure compliance with the requirements
                of Rule
                419, that being the sole responsibility of the Company and the
                Founders.

            


    

     

    
      	2.	
              ESCROW
                DEPOSITS:

            


    

     

    
      	
              2.1

            	
              The
                Escrow Agent shall accept deposits to the Escrow Account at the time
                and
                in the manner specified in paragraph 2.2. All securities delivered
                to the
                Escrow Agent shall, upon delivery, automatically become subject to
                the
                provisions of this Escrow
                Agreement.

            


    

     

    
      	
              2.2

            	
              Upon
                completion of the gift share distribution, the Founders shall jointly
                execute and deliver to the Escrow Agent a schedule that identifies
                the
                specific Gift Share transfers made by each Founder. When the Escrow
                Agent
                receives the duly authenticated documents evidencing the distribution
                of
                the Gift Shares, the identity of the Donees and complete information
                respecting the Donee’s name, mailing address and taxpayer identification
                number, the Escrow Agent shall examine the documentation to confirm
                that
                the stockholder information complies in all particulars with the
                supporting schedules and the Company shall promptly correct any errors,
                omissions or inconsistencies noted by the Escrow Agent. When all
                documents
                of transfer have been examined and approved by the Escrow Agent,
                the Gift
                Shares shall be promptly re-registered in the names of individual
                Donees
                by the Company, or if a transfer agent is appointed for the Company,
                by
                the transfer agent. 

            


    

     

    
      
        
        

      

      
        
        

        
          

        

      

      
        
        

      

    

     

    
      	
              2.3

            	
              Additional
                escrow deposits in the form of duly authenticated documents evidencing
                the
                planned resale or transfer of Founders’ Shares may be made from time to
                time during the term of this Agreement. When any of the Founders
                enter
                into an agreement to sell all or any part of the Founders’ Shares, they
                shall promptly deliver duly authenticated copies of the applicable
                agreements to the Escrow Agent. All such securities shall remain
                registered in the name of the Founders, but the Escrow Agent’s records
                shall be annotated to appropriately reflect the rights of the potential
                purchaser. All contracts for the sale of Founders Shares shall be
                contingent upon the successful closing of an acquisition and be
                accompanied by such additional documentation as the Company, the
                Founders
                and the Escrow Agent deem necessary or desirable to comply with the
                requirements of Rule 419, or otherwise provide for the efficient
                performance of the Escrow Agent’s duties
                hereunder.

            


    

     

    
      	
              2.4

            	
              All
                stock securities delivered to the Escrow Agent pursuant to the provisions
                of this Section 2 shall be held and disposed of by Escrow Agent in
                accordance with the following instructions and upon the terms and
                conditions set forth herein.

            


    

     

    
      	3.	
              TERMINATION
                AND DISBURSEMENTS:

            


    

     

    
      	
              3.1

            	
              If
                the Company has not negotiated an acquisition transaction, filed
                a
                post-effective amendment to its registration statement, successfully
                completed a reconfirmation offering meeting the requirements of
                Rule 419 and closed on the acquisition agreement within 18 months
                after the effective date of its registration statement (the “Final
                Termination Date”), the Escrow Agent
                shall:

            


    

     

    
      	 	
              (a)

            	
              Return
                all Gift Shares to the Founders;
                and

            


    

     

    
      	 	
              (b)

            	
              Return
                all Founders’ Shares to the
                Founders.

            


    

     

    When
      all
      Gift Shares and Founders’ Shares have been returned to the Founders in
      accordance with the provisions of this Paragraph 3.1, this Escrow Agreement
      will
      terminate.

     

    
      	
              3.2

            	
              If
                the Company negotiates an acquisition, files a post-effective amendment
                to
                its registration statement and conducts a reconfirmation offering
                meeting
                the requirements of Rule 419; and the terms of such offering are not
                accepted by the number of Gift Share Donees specified in the definitive
                prospectus included in the Company’s post-effective amendment, the Company
                shall immediately notify the Escrow Agent that the terms of its
                reconfirmation offering have been rejected by the Gift Share Donees
                and
                the Escrow Agent shall:

            


    

     

    
      
        
          	
                	(a)	
                  Return
                    all Gift Shares to the Founders;
                    and

                


        

      

    

     

    
      
        
          	
                	(b)	
                  Return
                    all Founders’ Shares to the
                    Founders.

                


        

      

    

     

    When
      all
      securities have been returned to the Founders in accordance with the provisions
      this Paragraph 3.2, this Escrow Agreement will terminate.

     

    
      	
              3.3

            	
              If
                the Company negotiates an acquisition, files a post-effective amendment
                to
                its registration statement and conducts a reconfirmation offering
                meeting
                the requirements of Rule 419 and the terms of such offering are
                accepted by the number of Gift Share Donees specified in the definitive
                prospectus included in the Company’s post-effective amendment, the Company
                shall promptly deliver, or cause to be delivered, to the Escrow
                Agent:

            


    

     

    
      	 	
              (a)

            	
              A
                copy of the definitive prospectus included in its post-effective
                amendment
                and used in connection with the reconfirmation
                offering;

            


    

     

    
      	 	
              (b)

            	
              A
                schedule setting forth the identity of each Donee who has approved
                the
                terms of the reconfirmation offering in writing;
                and

            


    

     

    
      	 	
              (c)

            	
              A
                schedule setting forth the identity of each Donee who has rejected
                the
                terms of the reconfirmation offering in writing or otherwise failed
                to
                execute a reconfirmation agreement within the time limits specified
                in the
                definitive prospectus.

            


    

     

    Upon
      receipt of the foregoing documentation, the Escrow Agent shall return to the
      Founders all securities registered in the names of Donees who refused or failed
      to execute a reconfirmation agreement within the time limits specified in the
      definitive prospectus. Gift Shares held on behalf of Donees who approved the
      reconfirmation offering shall be retained in escrow until the conditions of
      Section 3.4 are satisfied.

     

    
      	
              3.4

            	
              If
                the Company satisfies the conditions of Paragraph 3.3, actually closes
                the
                business combination described in the post-effective amendment to
                its
                registration statement and delivers to the Escrow Agent a Certificate
                signed by the President and Secretary that all conditions precedent
                to the
                final release of stock certificates set forth in Rule 419(e)(3) have
                been satisfied, the Escrow Agent
                shall:

            


    

     

    
      
        
        

      

      
        
        

        
          

        

      

      
        
        

      

    

     

    
      
        
          	
                	(a)	
                  Mail
                    stock certificates to each Donee who received Common Stock in
                    connection
                    with the Gift Share distribution and subsequently executed a
                    reconfirmation agreement;
                    and

                


        

      

    

     

    
      
        
          	
                	(b)	
                  Deliver
                    stock certificates for the Founders’ Shares to the closing agents
                    specified in the associated stock purchase agreements; but only
                    if a
                    closing agent was specified in the purchase agreement delivered
                    to the
                    Escrow Agent. In the event that a closing agent was not so specified,
                    the
                    Escrow Agent shall retain possession of the stock certificates
                    pending its
                    receipt of joint written instructions from the Founders and the
                    purchasers
                    of Founders Shares.

                


        

      

    

     

    When
      all
      securities and Escrow Funds deposited with the Escrow Agent have been disbursed
      in accordance with the provisions of this Paragraph 3.4, this Escrow Agreement
      will terminate.

     

    
      	
              4.

            	
              NO
                MODIFICATION:

            


    

     

    
      	
              4.1

            	
              After
                the effective date of the Registration Statement, these instructions
                shall
                not be modified, rescinded or amended without the written consent
                of each
                Donee and each purchaser of Founders’ Shares who may be adversely affected
                by such modification, rescission or
                amendment.

            


    

     

    
      	5.	
              GENERAL
                PROVISIONS:

            


    

     

    
      	
              5.1

            	
              All
                parties understand and agree that Escrow Agent is not a principal,
                participant, or beneficiary of the underlying transaction that
                necessitates this Escrow Agreement. The Escrow Agent shall be obligated
                only for the performance of such duties as are specifically set forth
                herein and may rely and shall be protected in acting or refraining
                from
                acting on any instrument believed by it to be genuine and to have
                been
                signed or presented by the proper party or parties, their officers,
                representatives or agents. The Escrow Agent shall not be liable for
                any
                action taken or omitted by it in good faith and believed by it to
                be
                authorized hereby, nor for action taken or omitted by it in accordance
                with the advice of its counsel. Escrow Agent shall be responsible
                for
                holding, investing and disbursing the Escrowed Assets pursuant to
                the
                Escrow Agreement, but in no event shall be liable for any exemplary
                or
                consequential damages in excess of Escrow Agent’s fee
                hereunder.

            


    

     

    
      	
              5.2

            	
              Unless
                otherwise provided herein, the Escrow Agent shall accept, hold and
                distribute the Escrowed Assets pursuant to this Escrow Agreement.
                Acceptance of the Escrowed Assets shall be communicated by Escrow
                Agent to
                parties in writing as soon as practicable after receipt, and any
                discrepancies shall be noted to Escrow Agent by the parties in writing
                within forty five (45) days of receiving such communication. Failure
                to
                note any discrepancies shall be deemed confirmation of the description
                of
                Escrowed Assets listed on the report regardless of any variations
                from the
                original schedule.

            


    

     

    
      	
              5.3

            	
              Should
                any controversy arise between the undersigned with respect to this
                Escrow
                Agreement or with respect to the right to receive the Escrowed Assets,
                Escrow Agent shall have the right to consult counsel and/or to institute
                a
                bill of interpleader in any court of competent jurisdiction to determine
                the rights of the parties. In the event it is a party to any dispute,
                Escrow Agent shall have the additional right to refer such controversy
                to
                binding arbitration. Should such actions be necessary, or should
                Escrow
                Agent become involved in litigation in any manner whatsoever on account
                of
                this Escrow Agreement or the Escrowed Assets, the undersigned hereby
                bind
                and obligate themselves, their heirs and legal representatives to
                pay
                Escrow Agent, in addition to any charge made hereunder for acting
                as
                Escrow Agent, reasonable attorney’s fees incurred by Escrow Agent, and any
                other disbursements, expenses, losses, costs and damages in connection
                with and resulting from such
                actions.

            


    

     

    
      	
              5.4

            	
              The
                Escrow Agent shall have no liability under, or duty to inquire beyond
                the
                terms and provisions of the Escrow Agreement, and it is agreed that
                its
                duties are purely ministerial in nature, and that the Escrow Agent
                shall
                incur no liability whatsoever except for its own willful misconduct
                or
                gross negligence so long as it has acted in good faith. The Escrow
                Agent
                shall not be bound by any modification, amendment, termination,
                cancellation, rescission or supersession of this Escrow Agreement
                unless
                the same shall be in writing and signed by all of the other parties
                hereto
                and, if its duties as Escrow Agent hereunder are affected thereby,
                unless
                it shall have given prior written consent thereto. IN NO EVENT SHALL
                THE
                ESCROW AGENT BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
                LOSSES
                OR DAMAGES OF ANY KIND WHATSOEVER (INCLUDING WITHOUT LIMITATION LOST
                PROFITS), EVEN IF THE ESCROW AGENT HAS BEEN ADVISED OF THE POSSIBILITY
                OF
                SUCH LOSSES OR DAMAGES AND REGARDLESS OF THE FORM OF
                ACTION.

            


    

     

    
      	
              5.5

            	
              The
                Escrow Agent may at any time resign hereunder by giving written notice
                of
                its resignation to the other parties hereto, at their address set
                forth
                herein, at least ten (10) days prior to the date specified for such
                resignation to take effect, and upon the effective date of such
                resignation, the Escrowed Assets hereunder shall be delivered to
                such
                person as may be designated in writing by the parties executing this
                Escrow Agreement, whereupon all the Escrow Agent’s obligations hereunder
                shall cease and terminate. The Escrow Agent’s sole responsibility until
                such termination shall be to keep safely all Escrowed Assets and
                to
                deliver the same to a person designated by the parties executing
                this
                Escrow Agreement or in accordance with the directions of a final
                order or
                judgment of a court of competent
                jurisdiction.

            


    

     

    
      
        
        

      

      
        
        

        
          

        

      

      
        
        

      

    

     

    
      	
              5.6

            	
              The
                parties agree to jointly and severally indemnify, defend and hold
                the
                Escrow Agent harmless from and against any and all loss, damage,
                tax,
                liability and expense that may be incurred by the Escrow Agent arising
                out
                of or in connection with its acceptance or appointments as Escrow
                Agent
                hereunder, including costs and expenses of defending itself against
                any
                claim or liability in connection with its performance hereunder.
                The
                obligations of the parties under this Section 5.6 shall survive the
                termination of this Letter of Escrow Instructions and the resignation
                or
                removal of the Escrow Agent.

            


    

     

    
      	
              5.7

            	
              The
                parties jointly and severally agree to pay to the Escrow Agent its
                fees
                for the services rendered pursuant to the provisions of this Escrow
                Agreement and will reimburse the Escrow Agent for reasonable expenses,
                including reasonable attorney’s fees incurred in connection with the
                negotiations, drafting and performance of such services. Except as
                otherwise noted, this fee covers account acceptance, set up and
                termination expenses; plus usual and customary related administrative
                services such as safekeeping, investment and payment of funds specified
                herein or in the exhibits attached. Activities requiring excessive
                administrator time or out-of-pocket expenses such as optional substitution
                of collateral or securities shall be deemed extraordinary expenses
                for
                which related costs, transaction charges, and additional fees will
                be
                billed at Escrow Agent’s standard charges for such items. A fee schedule
                has been provided to all parties to this Escrow
                Agreement.

            


    

     

    
      	
              5.8

            	
              Escrow
                Agent is hereby given a lien on all Escrowed Assets for all fees,
                expenses
                and indemnification payments that may become owing to Escrow Agent
                hereunder, which lien may be enforced by Escrow Agent by setoff or
                appropriate foreclosure
                proceedings.

            


    

     

    
      	
              5.9

            	
              The
                parties warrant to the Escrow Agent that there are no Federal, State
                or
                local tax liability or filing requirements whatsoever concerning
                the
                Escrow Agent’s actions contemplated hereunder and warrant and represent to
                the Escrow Agent that the Escrow Agent has no duty to withhold or
                file any
                report of any tax liability under any Federal of State income tax,
                local
                or State property tax, local or State sales or use taxes, or any
                other tax
                by any taxing authority. The parties hereto agree to jointly and
                severally
                indemnify the Escrow Agent fully for any tax liability, penalties
                or
                interest incurred by the Escrow Agent arising hereunder and agree
                to pay
                in full any such tax liability together with penalty and interest
                if any
                tax liability is ultimately assessed against the Escrow Agent for
                any
                reason as a result of its action hereunder (except for the Escrow
                Agent’s
                individual income tax liability arising from its income
                fees).

            


    

     

    
      	
              5.10

            	
              The
                Escrow Agent shall have no liability for loss arising from any cause
                beyond its control, including, but not limited to, the following:
                (a) the
                act, failure or neglect of any agent or correspondent selected by
                the
                Escrow Agent or the parties hereto; (b) any delay, error, omission
                or
                default connected with the remittance of funds; (c) any delay, error,
                omission or default of any mail, telegraph, cable or wireless agency
                or
                operator; and (d) the acts or edicts of any government or governmental
                agency or other group or entity exercising governmental
                powers.

            


    

     

    
      	
              5.11

            	
              This
                Escrow Agreement shall be governed by and construed in accordance
                with the
                laws of the State of Texas.

            


    

     

    
      	
              6.

            	
              NOTICES:

            


    

     

    
      	
              6.1

            	
              All
                notices, demands, requests or payments provided for or given pursuant
                to
                this Escrow must be in writing or facsimile. All such notices shall
                be
                deemed to have been properly given or served by personal delivery
                or by
                depositing the same in the United States mail addressed to the person
                entitled to receive such notice at the address set forth
                below.

            


    

     

    
      	
              To
                the Company and Founders

            	
              To
                the Escrow Agent

            
	
              Sally
                A. Fonner, President

            	
              Wells
                Fargo Bank, N.A.

            
	
              Stirling
                Acquisition Corporation 

            	
              Corporate
                Trust and Escrow Services

            
	
              914
                Curlew Road, Suite 403

            	
              201
                Main Street, Suite 301

            
	
              Dunedin,
                Florida 34698

            	
              Fort
                Worth, Texas 76102

            
	
              Facsimile:
                (727) 683-9573

            	
              Facsimile:
                (817) 885-8650

            


    

     

    
      	
              6.2

            	
              All
                notices shall be effective when
                received.

            


    

    


    
      
        
        

      

      
        
        

        
          

        

      

      
        
        

      

    

    


    Approved
      and accepted by the Company and the Escrow Agent this 1st day of August
      2007.

     

    
      	Stirling Acquisition
              Corporation 	 	Wells Fargo Bank,
              N.A.,
              not personally but solely  
	 	 	as Escrow Agent 
	 	 	 	 	 
	By:	
              /s/ MARK R. DOLAN

              
                

              
Mark R. Dolan, Vice President	 	By:	
              /s/ JOHN C. STOHLMANN

              
                

              
John C. Stohlmann
	 	 	 	 	 


    

     

    Approved
      and accepted by the Founders this 1st
      day of August 2007.

     

    
      	Sally A. Fonner  	 	Mark R. Dolan 
	 	 	 	 	 
	/s/ SALLY A. FONNER 	 	/s/ MARK R.
              DOLAN 
	 	 	 	 	 
	John L. Petersen 	 	Rachel A. Fefer 
	 	 	 	 	 
	/s/ JOHN L.
              PETERSEN 	 	/s/ RACHEL A.
              FEFER