Initial Unit Subscription Agreement with David M. Schizer



 Exhibit 10.21 
 ROCK ACQUISITION CORP. 
 INITIAL UNIT SUBSCRIPTION AGREEMENT 
 THIS INITIAL UNIT SUBSCRIPTION AGREEMENT (this “Agreement”) is made as of the 2nd day of October, 2007, by and between Rock Acquisition Corp., a Delaware corporation (the “Company”), and David M. Schizer (“Purchaser”).

 WHEREAS, the Company desires to issue and sell, and Purchaser desires to purchase and acquire, Units (as defined herein) on the
terms and conditions hereinafter set forth; 
 NOW, THEREFORE, for and in consideration of the promises and mutual covenants set forth
herein, it is agreed between the parties as follows: 
 1. Purchase of Units. Purchaser hereby subscribes for and purchases from the
Company, and the Company hereby issues and sells to Purchaser, 46,000 units (the “Units”) at a purchase price of $0.01 per Unit for an aggregate purchase price of $460. Each Unit consists of one share of the common stock of the Company,
par value $0.001 per share (the “Common Stock”), and one warrant (a “Warrant” and, together with the Units and the Common Stock, the “Securities”) exercisable for one share of Common Stock. Each Warrant shall entitle
the holder thereof to purchase one share of Common Stock at an exercise price of $7.50, in accordance with the terms of the Warrant substantially as set forth in the Form of Warrant Agreement attached hereto as Exhibit A (the “Warrant
Agreement”) to be entered into by and between the Company and a warrant agent to be named by the Company and shall be subject to the terms of the Warrant Agreement upon execution thereof. 
 2. Payment of Purchase Price. The purchase price for the Units shall be tendered in full on the date hereof. 
 3. Redemption of Units. If the underwriters (the “Underwriters”) in the Company’s initial public offering (the “IPO”) do
not exercise in full their over-allotment option to be granted by the Company pursuant to an underwriting agreement by and among the Underwriters and the Company, then either (i) the Company shall redeem from Purchaser, at a redemption price
equal to $0.01 per Unit, or (ii) the Purchaser shall forfeit, a number of Units equal to 6,000 multiplied by the percentage of the Underwriters’ over-allotment option that remains unexercised as of the expiration date thereof. 

4. Limitations on Transfer. Purchaser shall not assign, hypothecate, donate, encumber or otherwise dispose of any interest in the Securities
(and the underlying securities) during the “Escrow Period” for the “Founder Units” (as such terms are defined in a securities escrow agreement substantially in the form attached hereto as Exhibit B (the “Securities Escrow
Agreement”), dated on or about the effective date of the IPO to be entered into by and between the Company and an escrow agent to be determined by the Company), except (i) as otherwise permitted by the Securities Escrow Agreement,
(ii) in compliance with applicable securities laws and (iii) in compliance with the Warrant Agreement. 
 5. Restrictive
Legends. All certificates representing the Securities (and any underlying securities thereof) shall have endorsed thereon legends in substantially the following forms (in addition to any other legend which may be required by other agreements
between the parties hereto): 
 (a) “THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE
SECURITIES ACT OF 1933, AS AMENDED. THE SECURITIES MAY NOT BE SOLD, OFFERED FOR SALE, PLEDGED OR HYPOTHECATED IN THE ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT AS TO THE SECURITIES UNDER SAID ACT OR AN OPINION OF COUNSEL SATISFACTORY TO THE
COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED.” 
  

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 (b) “THE SECURITIES REPRESENTED BY THIS CERTIFICATE MAY NOT BE ASSIGNED,
HYPOTHECATED, DONATED, ENCUMBERED, SOLD, TRANSFERRED OR OTHERWISE DISPOSED OF EXCEPT IN ACCORDANCE WITH THAT CERTAIN SECURITIES ESCROW AGREEMENT DATED AS OF
                    , 2007, COPIES OF WHICH ARE AVAILABLE FOR INSPECTION AT THE OFFICES OF THE COMPANY.” 
 (c) Any legend required by appropriate blue sky officials. 
 6. Investment Representations. In connection with the purchase of the Securities, Purchaser represents to the Company the following: 
 (a) Purchaser has been furnished with all materials relating to the Company’s business affairs and financial condition and materials
related to the offer and sale of the Securities that have been requested by Purchaser and has acquired sufficient information about the Company to reach an informed and knowledgeable decision to acquire the Securities. Purchaser has been afforded
the opportunity to ask questions of the executive officers and directors of the Company. Purchaser understands that its investment in the Securities involves a high degree of risk. Purchaser has sought such accounting, legal and tax advice as
Purchaser has considered necessary to make an informed investment decision with respect to Purchaser’s acquisition of the Securities. Purchaser has such knowledge and expertise in financial and business matters, knows of the high degree of risk
associated with investments generally and particularly investments in the securities of companies in the development stage such as the Company, is capable of evaluating the merits and risks of an investment in the Securities, and is able to bear the
economic risk of an investment in the Securities in the amount contemplated hereunder. Purchaser has adequate means of providing for its current financial needs and contingencies and will have no current or anticipated future needs for liquidity
which would be jeopardized by the investment in the Securities. Purchaser can afford a complete loss of its investment in the Securities. Purchaser is purchasing the Securities for investment for Purchaser’s own account only and not with a view
to, or for resale in connection with, any “distribution” thereof within the meaning of the Securities Act of 1933, as amended (the “Act”). Purchaser understands that the Company is a blank check development stage company recently
formed for the purpose of consummating an initial business combination (a “Business Combination”) and understands that there is no assurance as to the future performance of the Company and that the Company may never effectuate a Business
Combination. 
 (b) Purchaser understands that the Securities (and the underlying securities thereof) have not been registered
under the Act or any state securities law by reason of a specific exemption therefrom, and that the Company is relying on the truth and accuracy of, and Purchaser’s compliance with, the representations and warranties and agreements of Purchaser
set forth herein to determine the availability of such exemptions and the eligibility of Purchaser to acquire such Securities, including, but not limited to, the bona fide nature of Purchaser’s investment intent as expressed herein. 

(c) Purchaser further acknowledges and understands that the Securities (and the underlying securities thereof) must be held
indefinitely unless the Securities (and the underlying securities thereof) are subsequently registered under the Act or an exemption from such registration is available. Purchaser understands that the certificates evidencing the Securities (and the
underlying securities thereof) will be imprinted with a legend which prohibits the transfer of the Securities (and the underlying securities thereof) unless the Securities (and the underlying securities thereof) are registered or such registration
is not required in the opinion of counsel for the Company. 
  

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 (d) Purchaser is familiar with the provisions of Rule 144 under the Act, as in effect
from time to time (“Rule 144”), which, in substance, permit limited public resale of “restricted securities” acquired, directly or indirectly, from the issuer thereof (or from an affiliate of such issuer), in a non-public
offering subject to the satisfaction of certain conditions. Unless the Company registers the Securities (and the underlying securities thereof) under the Act, the Securities (and the underlying securities thereof) may be resold by Purchaser only in
certain limited circumstances subject to the provisions of Rule 144, which requires, among other things: (i) the availability of certain public information about the Company and (ii) the resale occurring following the required holding
period under Rule 144 after Purchaser has purchased, and made full payment of (within the meaning of Rule 144), the securities to be sold. 
 (e) Purchaser further understands that at the time Purchaser wishes to sell the Securities there may be no public market upon which to make such a sale, and that, even if such a public market then exists, the Company
may not be satisfying the current public information requirements of Rule 144, and that, in such event, Purchaser would be precluded from selling the Securities (and the underlying securities thereof) under Rule 144 even if the minimum holding
period requirement had been satisfied. Notwithstanding Sections 6(d) and (e) hereof, Purchaser understands that it may be considered a promoter of the Company and understands that it is the position of the Securities and Exchange Commission
(the “SEC”) that promoters or affiliates of a blank check company and their transferees, both before and after a Business Combination, would act as an “underwriter” under the Act when reselling the securities of a blank check
company. Accordingly, the SEC believes that those securities can be resold only through a registered offering and that Rule 144 would not be available for those resale transactions despite technical compliance with the requirements of Rule 144.

 (f) Purchaser represents that Purchaser is an “accredited investor” as that term is defined in Rule 501 of
Regulation D promulgated by the SEC under the Act. 
 (g) Purchaser has all necessary power and authority to enter into this
Agreement and to consummate the transactions contemplated hereby. This Agreement has been duly executed and delivered by Purchaser. Subject to the terms and conditions of this Agreement, this Agreement constitutes the valid, binding and enforceable
obligation of Purchaser, enforceable in accordance with its terms, except as enforceability may be limited by (i) applicable bankruptcy, insolvency, reorganization, moratorium, fraudulent transfer or similar laws of general application now or
hereafter in effect affecting the rights and remedies of creditors and by general principles of equity (regardless of whether enforcement is sought in a proceeding at law or in equity); and (ii) the applicability of the federal and state
securities laws and public policy as to the enforceability of the indemnification provisions of this Agreement. The purchase by Purchaser of the Securities does not conflict with any material contract by which Purchaser or his property is bound, or
any laws or regulations or decree, ruling or judgment of any court applicable to Purchaser or his property. The principal place of business of Purchaser is as set forth on the signature page hereto. 
 (h) Purchaser did not decide to enter into this Agreement as a result of any general solicitation or general advertising within the
meaning of Rule 502(c) of the Securities Act. 
 (i) Purchaser understands that no United States federal or state agency or
any other government or governmental agency has passed on or made any recommendation or endorsement of the Securities or the fairness or suitability of the investment in the Securities, nor have such authorities passed upon or endorsed the merits of
the offering of the Securities. 
 7. Company Representations and Warranties. The Company hereby represents and warrants to Purchaser
that the Company has all necessary corporate power and authority to enter into this Agreement and to consummate the transactions contemplated hereby. All corporate action necessary to be 

  

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taken by the Company to authorize the execution, delivery and performance of this Agreement and all other agreements and instruments delivered by the Company
in connection with the transactions contemplated hereby has been duly and validly taken and this Agreement has been duly executed and delivered by the Company. Subject to the terms and conditions of this Agreement, this Agreement constitutes the
valid, binding and enforceable obligation of the Company, enforceable in accordance with its terms, except as enforceability may be limited by (i) applicable bankruptcy, insolvency, reorganization, moratorium, fraudulent transfer or similar
laws of general application now or hereafter in effect affecting the rights and remedies of creditors and by general principles of equity (regardless of whether enforcement is sought in a proceeding at law or in equity); and (ii) the
applicability of the federal and state securities laws and public policy as to the enforceability of the indemnification provisions of this Agreement. The sale by the Company of the Securities does not conflict with the certificate of incorporation
or by-laws of the Company or any material contract by which the Company or its property is bound, or any federal or state laws or regulations or decree, ruling or judgment of any United States or state court applicable to the Company or its
property. 
 8. Indemnification. Purchaser hereby agrees to indemnify and hold harmless the Company and the Company’s officers,
directors, stockholders, employees, agents, and attorneys against any and all losses, claims, demands, liabilities and expenses (including reasonable legal or other expenses incurred by each such person in connection with defending or investigating
any such claims or liabilities, whether or not resulting in any liability to such person or whether incurred by the indemnified party in any action or proceeding between the indemnitor and indemnified party or between the indemnified party and any
third party) to which any such indemnified party may become subject, insofar as such losses, claims, demands, liabilities and expenses (a) arise out of or are based upon any untrue statement or alleged untrue statement of a material fact made
by Purchaser and contained herein, or (b) arise out of or are based upon any breach by Purchaser of any representation, warranty or agreement made by Purchaser contained herein. 
 9. Miscellaneous. 
 (a) Notices. All notices required or permitted hereunder shall be in writing and shall be deemed effectively given: (i) upon personal delivery to the party to be notified, (ii) when sent by confirmed facsimile if sent
during normal business hours of the recipient, and if not during normal business hours of the recipient, then on the next business day, (iii) five calendar days after having been sent by registered or certified mail, return receipt requested,
postage prepaid, or (iv) one business day after deposit with a nationally recognized overnight courier, specifying next day delivery, with written verification of receipt. All communications shall be sent to the other party hereto at such
party’s address hereinafter set forth on the signature page hereof, or at such other address as such party may designate by ten days advance written notice to the other party hereto. 
 (b) Successors and Assigns. This Agreement shall inure to the benefit of the successors and assigns of the Company and, subject to
the restrictions on transfer herein set forth, shall be binding upon Purchaser and Purchaser’s successors and assigns. 
 (c) Attorneys’ Fees; Specific Performance. Purchaser shall reimburse the Company for all costs incurred by the Company in enforcing the performance of, or protecting its rights under, any part of this Agreement, including
reasonable costs of investigation and attorneys’ fees. 
 (d) Governing Law; Venue. This Agreement shall be
governed by and construed in accordance with the laws of the State of Delaware without regard to the principles of conflicts of law thereof. The parties agree that any action brought by either party to interpret or enforce any provision of this
Agreement shall be brought in, and each party agrees to, and does hereby, submit to the jurisdiction and venue of, the appropriate state or federal court for the district encompassing the Company’s principal place of business. 
  

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 (e) Further Execution. The parties agree to take all such further action(s) as may
reasonably be necessary to carry out and consummate this Agreement as soon as practicable, and to take whatever steps may be necessary to obtain any governmental approval in connection with or otherwise qualify the issuance of the securities that
are the subject of this Agreement. 
 (f) Independent Counsel. Purchaser acknowledges that this Agreement has been
prepared on behalf of the Company by Skadden, Arps, Slate, Meagher & Flom LLP, counsel to the Company and that Skadden, Arps, Slate, Meagher & Flom LLP does not represent, and is not acting on behalf of, Purchaser. Purchaser has
been provided with an opportunity to consult with Purchaser’s own counsel with respect to this Agreement. 
 (g)
Entire Agreement; Amendment. This Agreement constitutes the entire agreement between the parties with respect to the subject matter hereof and supersedes and merges all prior agreements or understandings, whether written or oral. This
Agreement may not be amended, modified or revoked, in whole or in part, except by an agreement in writing signed by each of the parties hereto. 
 (h) Severability. If one or more provisions of this Agreement are held to be unenforceable under applicable law, the parties agree to renegotiate such provision in good faith. In the event that the parties
cannot reach a mutually agreeable and enforceable replacement for such provision, then (i) such provision shall be excluded from this Agreement, (ii) the balance of the Agreement shall be interpreted as if such provision were so excluded
and (iii) the balance of the Agreement shall be enforceable in accordance with its terms. 
 (i) Counterparts.
This Agreement may be executed in two or more counterparts, each of which shall be deemed an original and all of which together shall constitute one instrument. This Agreement or any counterpart may be executed via facsimile or electronic mail
transmission, and any such executed facsimile or electronic mail copy shall be treated as an original. 
 (j) Survival.
The representations and warranties contained herein will survive the delivery of, and the payment for, the Securities. 
 (k)
Waiver of Jury Trial. Each party hereto hereby irrevocably and unconditionally waives the right to a trial by jury in any action, suit, counterclaim or other proceeding (whether based on contract, tort or otherwise) arising out of, connected
with or relating to this Agreement, the transactions contemplated hereby, or the actions of Purchaser in the negotiation, administration, performance or enforcement hereof. 
  

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 IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of the day and year first above
written. 
  

					
	COMPANY:
	
	ROCK ACQUISITION CORP.
		
	By:	 	/s/ Donald G. Drapkin
		 	Name:	 	Donald G. Drapkin
		 	Title:	 	Chief Executive Officer and President
	
	PURCHASER:
		
	By:	 	/s/ David M. Schizer
		 	Name: 	 	David M. Schizer


  

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