Exhibit 4.1


 


	NUMBER	UNITS
	U-	 


 


SEE REVERSE FOR CERTAIN DEFINITIONS


 


CUSIP 623006 202


Mount Rainier Acquisition Corp.


 





UNITS CONSISTING OF ONE SHARE OF COMMON STOCK
AND ONE WARRANT TO PURCHASE THREE-FOURTHS OF ONE SHARE OF COMMON STOCK

  


THIS CERTIFIES THAT                     
is the owner of          Units.


 


Each Unit (“Unit”)
consists of one (1) share of common stock, par value $0.0001 per share (“Common Stock”), of Mount Rainier
Acquisition Corp., a Delaware corporation (the “Company”), and one redeemable warrant (the “Warrant”). Each
Warrant entitles the holder thereof to purchase three-fourths (3/4) of one (1) share of Common Stock at a price of $11.50 per share (subject
to adjustment). Only whole Warrants are exercisable. Each whole Warrant will become exercisable on the later of (i) thirty (30) days
after the Company’s completion of a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or other similar
business combination with one or more businesses (each a “Business Combination”), or (ii) twelve (12) months
from the closing of the Company’s initial public offering, and, unless exercised earlier, will expire at 5:00 p.m., New York City
Time, on the date that is five (5) years after the date on which the Company completes its initial Business Combination, or earlier
upon redemption thereof or Company’s liquidation. The Common Stock and Warrants comprising the Units represented by this certificate
are not transferable separately prior to [•], 2021, unless A.G.P./Alliance Global Partners elects to allow separate trading
earlier, subject to the Company’s filing of a Current Report on Form 8-K with the Securities and Exchange Commission containing
an audited balance sheet reflecting the Company’s receipt of the gross proceeds of the Company’s initial public offering and
the Company issuing a press release announcing when separate trading will begin. The terms of the Warrants are governed by a Warrant
Agreement, dated as of [•], 2021, between the Company and American Stock Transfer & Trust Company, as Warrant Agent, and
are subject to the terms and provisions contained therein, all of which terms and provisions the holder of this certificate consents to
by acceptance hereof. Copies of the Warrant Agreement are on file at the office of the Warrant Agent at 6201 15th Avenue Brooklyn,
NY 11219, and are available to any Warrant holder on written request and without cost.


 


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


 


This certificate shall be governed
by and construed in accordance with the internal laws of the State of New York.


 


Witness the facsimile signature
of a duly authorized signatory of the Company.


 


	 	 	 	 	 
	Authorized Signatory	 	 	 	Transfer Agent and Registrar


 






     


     


    

 


Mount Rainier Acquisition Corp.


 


The Company will furnish
without charge to each unitholder 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.


 


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 sell, assign and transfer unto                     


 


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


 


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


 


Units represented by the within Certificate,
and do hereby irrevocably constitute and appoint


 


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


 


Dated


 


	 	 
	 	 
	 	Notice: The signature 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:	 
	 	 
	 	 
	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 (OR ANY SUCCESSOR RULE).	 


 


 


 


 






     


     


    

 


In each case, as more
fully described in the Company’s final prospectus 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 the Company’s initial public
offering only in the event that (i) the Company redeems the shares of Common Stock sold in the Company’s initial public offering
and liquidates because it does not consummate an initial business combination by [•], 2023 (or such later date as the Company’s
amended and restated certificate of incorporation may be amended to provide for), (ii) the Company offers to redeem the shares of
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 (A) to modify the substance or timing of the Company’s obligation to allow redemption in connection
with the Company’s initial business combination or certain amendments to the Company’s certificate of incorporation prior
thereto or to redeem 100% of such Common Stock if it does not consummate an initial business combination by [•], 2023 or (B) with
respect to any other provision relating to stockholders’ rights or pre-initial business combination activity, and the holder(s)
of this certificate elects to have the shares of Common Stock held by him, her or it redeemed pursuant to that offer, or (iii) if
the holder(s) seek(s) to redeem for cash his, her or its respective shares of 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.