Exhibit 4.2


 


	NUMBER	 	NUMBER
	 	 	C-
	 	 	SHARES
	 	 	SEE REVERSE FOR CERTAIN DEFINITIONS
	 	 	CUSIP 812204 105


 


SEAPORT CALIBRE MATERIALS
ACQUISITION CORP.


 


INCORPORATED UNDER
THE LAWS OF THE STATE OF DELAWARE 

CLASS A COMMON STOCK


 


This certifies that


 


is the owner of


 


FULLY PAID AND NON-ASSESSABLE
SHARES OF THE PAR VALUE OF $0.0001 EACH OF THE CLASS A COMMON STOCK OF


 


SEAPORT CALIBRE MATERIALS
ACQUISITION CORP.

(THE “COMPANY”)


 


transferable on the books
of the Company in person or by duly authorized attorney upon surrender of this certificate properly endorsed.


 


The Company will be forced
to redeem all of its shares of Class A common stock if it is unable to complete a business combination by                      ,
2023, all as more fully described in the Company’s final prospectus dated                        ,
2021.


 


This certificate is not
valid unless countersigned by the Transfer Agent and registered by the Registrar of the Company.


 


Witness the seal of the
Company and the facsimile signatures of its duly authorized officers.


 





	Chief Executive Officer	 	[Corporate Seal] Delaware	Chief Financial Officer






	 	 	 	 


 









     


     


    

 


SEAPORT CALIBRE MATERIALS
ACQUISITION CORP.


 


The Company will furnish
without charge to each stockholder who so requests, a statement of the powers, designations, preferences and relative, participating,
optional or other special rights of each class of stock or series thereof of the Company and the qualifications, limitations, or restrictions
of such preferences and/or rights. This certificate and the shares represented thereby are issued and shall be held subject to all the
provisions of the Company’s amended and restated certificate of incorporation and all amendments thereto and resolutions of the
Board of Directors providing for the issue of securities (copies of which may be obtained from the secretary of the Company), to all of
which the holder of this certificate by acceptance hereof assents. The following abbreviations, when used in the inscription on the face
of this certificate, shall be construed as though they were written out in full according to applicable laws or regulations:


 


	TEN COM	—	as tenants in common	UNIF GIFT MIN ACT	—	 	Custodian	 
	 	 	 	 	 	 	 	 
	TEN ENT	—	as tenants by the entireties	 	 	(Cust)	 	(Minor)


  


	JT TEN	—	as joint tenants with right of survivorship and not as tenants in common	 	under Uniform Gifts to Minors Act
	 	 	 	 	 	(State)                    


 


Additional abbreviations may also be used
though not in the above list.


 


For value received,                   
hereby sells, assigns and transfers unto


 


(PLEASE INSERT SOCIAL
SECURITY OR OTHER IDENTIFYING NUMBER(S) OF ASSIGNEE(S))


 


(PLEASE PRINT OR TYPEWRITE
NAME(S) AND ADDRESS(ES), INCLUDING ZIP CODE, OF ASSIGNEE(S))


 


shares of the capital stock represented by
the within Certificate, and hereby irrevocably constitutes and appoints


 


Attorney to transfer
the said stock on the books of the within named Company with full power of substitution in the premises.


 


	Dated:	 
	 





	 
	 
	NOTICE: THE SIGNATURE(S) TO
THIS ASSIGNMENT MUST CORRESPOND WITH THE NAME AS WRITTEN UPON THE FACE OF THE CERTIFICATE IN EVERY PARTICULAR, WITHOUT ALTERATION OR ENLARGEMENT
OR ANY CHANGE WHATEVER.





 


	Signature(s) Guaranteed:	 
	By	 
	 


 


	 
	THE SIGNATURE(S) MUST
BE GUARANTEED BY AN ELIGIBLE GUARANTOR INSTITUTION (BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS AND CREDIT UNIONS WITH MEMBERSHIP
IN AN APPROVED SIGNATURE GUARANTEE MEDALLION PROGRAM, PURSUANT TO S.E.C. RULE 17Ad-15 UNDER THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED
(OR ANY SUCCESSOR RULE).





 


In each case, as
more fully described in, and subject to the terms and conditions described in, the Company’s final prospectus for its initial
public offering dated                   ,
2021, the holder(s) of this certificate shall be entitled to receive a pro-rata portion of certain funds held in the trust
account established in connection with its initial public offering only in the event that (i) the Company redeems the shares of
Class A common stock sold in the Company’s initial public offering and liquidates because it does not consummate an
initial business combination within the time period set forth in the Company’s amended and restated certificate of
incorporation, as the same may be amended from time to time (such date being referred to herein as the “Last Date”),
(ii) the Company redeems the shares of Class A common stock sold in its initial public offering in connection with a
stockholder vote to amend the Company’s amended and restated certificate of incorporation to modify the substance or timing of
the Company’s obligation to redeem 100% of the Class A common stock if it does not consummate an initial business
combination by the Last Date or with respect to any other provision relating to stockholders’ rights or pre-initial business
combination activity, or (iii) if the holder(s) seek(s) to redeem for cash his, her or its respective shares of
Class A common stock in connection with a tender offer (or proxy solicitation, solely in the event the Company seeks
stockholder approval of the proposed initial business combination) setting forth the details of a proposed initial business
combination. In no other circumstances shall the holder(s) have any right or interest of any kind in or to the trust
account.