Document:

Exhibit
4.2

 

SPECIMEN
CLASS A ORDINARY SHARE CERTIFICATE 

 

	NUMBER	 	SHARES

 

ONS
ACQUISITION CORP. 

INCORPORATED
UNDER THE LAWS OF THE CAYMAN ISLANDS 

CLASS
A ORDINARY SHARES 

 

SEE
REVERSE FOR 

CERTAIN
DEFINITIONS 

 

CUSIP
G67560105 

 

This
Certifies that                 is the owner of 

 

FULLY
PAID AND NON-ASSESSABLE CLASS A ORDINARY SHARES OF THE PAR VALUE OF 

US$0.0001
EACH OF ONS ACQUISITION CORP. (THE “COMPANY”) 

 

subject
to the Company’s amended and restated memorandum and articles of association, as the same may be amended from time to time, and
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 Class A ordinary shares if it is unable to complete a business combination within the period
set forth in the Company’s amended and restated memorandum and articles of association, as the same may be amended from time to
time, 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. 

 

Witness
the facsimile signatures of its duly authorized officers. 

 

	Dated:
    ______________________

	Chief
    Executive Officer	Cayman
    Islands	Chief
    Financial Officer
	 	 	 

 

     

     

    

 

ONS
ACQUISITION CORP.

 

The
Company will furnish without charge to each shareholder who so requests the powers, designations, preferences and relative, participating,
optional or other special rights of each class of shares 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 memorandum and articles of association, as the same may be amended from time to
time, and resolutions of the Board of Directors providing for the issue of Class A ordinary shares (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	 	 
	 	 	 	 	 	 	 	 
	 	 	 	 	 	 	 	 	 	 	(Cust)	 	 	 	(Minor)
	 	 	 	 	 	 
	TEN
    ENT	 	—	 	as
    tenants by the entireties	 	 	 	 	 	under
    Uniform Gifts to Minors Act
	 	 	 	 	 	 
	 	 	 	 	 	 	 	 	 	 	(State)
	 	 	 	 	 	 	 	 
	JT
    TEN	 	—	 	as
    joint tenants with right of survivorship and not as tenants in common	 	 	 	 	 	 	 	 	 	 

 

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
represented by the within Certificate, and does hereby irrevocably constitute and appoint Attorney to transfer the said shares on the
books of the within named Company with full power of substitution in the premises.

	 	 	 	 	 
	Dated:	 	 	 	 
	 	 	 	 	 
	 	 	 	 	Shareholder
	 	 	 	 
	 	 	 	 	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 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 its initial public
offering only in the event that (i) the Company redeems the Class A ordinary shares sold in its initial public offering and liquidates
because it does not consummate an initial business combination within the period of time set forth in the Company’s amended and
restated memorandum and articles of association, as the same may be amended from time to time, (ii) the Company redeems the Class A ordinary
shares sold in its initial public offering in connection with a shareholder vote to amend the Company’s amended and restated memorandum
and articles of association (A) that would modify the substance or timing of the Company’s obligation to provide holders of the
Class A ordinary shares the right to have their shares redeemed in connection with the Company’s initial business combination or
to redeem 100% of the Class A ordinary shares if the Company does not complete its initial business combination within the time period
set forth therein or (B) with respect to any other provision relating to the rights of holders of the Class A ordinary shares, or (iii)
if the holder(s) seek(s) to redeem for cash his, her or its respective Class A ordinary shares in connection with a tender offer (or
proxy solicitation, solely in the event the Company seeks shareholder 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.Exhibit 4.3

 

[FACE]

 

Number

 

Warrants 

 

THIS WARRANT SHALL BE VOID IF NOT EXERCISED
PRIOR TO 

THE EXPIRATION OF THE EXERCISE PERIOD PROVIDED
FOR 

IN THE WARRANT AGREEMENT DESCRIBED BELOW 

 

ONS Acquisition Corp. 

Incorporated Under the Laws of the Cayman Islands

 

CUSIP G67560139

 

Warrant Certificate 

 

This Warrant Certificate certifies that , or registered
assigns, is the registered holder of warrant(s) (the “Warrants” and each, a “Warrant”)
to purchase Class A ordinary shares, $0.0001 par value (“Ordinary Shares”), of ONS Acquisition Corp., a Cayman
Islands exempted company (the “Company”). Each Warrant entitles the holder, upon exercise during the period
set forth in the Warrant Agreement referred to below, to receive from the Company that number of fully paid and nonassessable Ordinary
Shares as set forth below, at the exercise price (the “Exercise Price”) as determined pursuant to the Warrant
Agreement, payable in lawful money (or through “cashless exercise” as provided for in the Warrant Agreement)
of the United States of America upon surrender of this Warrant Certificate and payment of the Exercise Price at the office or agency of
the Warrant Agent referred to below, subject to the conditions set forth herein and in the Warrant Agreement. Defined terms used in this
Warrant Certificate but not defined herein shall have the meanings given to them in the Warrant Agreement.

 

Each whole Warrant is initially exercisable for one fully paid and
non-assessable Ordinary Share. Fractional shares shall not be issued upon exercise of any Warrant. If, upon the exercise of Warrants,
a holder would be entitled to receive a fractional interest in an Ordinary Share, the Company shall, upon exercise, round down to the
nearest whole number the number of Ordinary Shares to be issued to the Warrant holder. The number of Ordinary Shares issuable upon exercise
of the Warrants is subject to adjustment upon the occurrence of certain events as set forth in the Warrant Agreement.

 

The initial Exercise Price per one Ordinary Share for any Warrant is
equal to $11.50 per share. The Exercise Price is subject to adjustment upon the occurrence of certain events as set forth in the Warrant
Agreement.

 

Subject to the conditions set forth in the Warrant Agreement, the Warrants
may be exercised only during the Exercise Period and to the extent not exercised by the end of such Exercise Period, such Warrants shall
become void. The Warrants may be redeemed, subject to certain conditions, as set forth in the Warrant Agreement.

 

Reference is hereby made to the further provisions of this Warrant
Certificate set forth on the reverse hereof and such further provisions shall for all purposes have the same effect as though fully set
forth at this place.

 

This Warrant Certificate shall not be valid unless countersigned by
the Warrant Agent, as such term is used in the Warrant Agreement. This Warrant Certificate shall be governed by and construed in accordance
with the internal laws of the State of New York.

  

	 	ONS ACQUISITION CORP.
	 	 	
	 	
    By:
	

	 	 	
    Name:
	
    Alexander Crutchfield

	 	 	Title:	Authorized Signatory
	 	 
	 	
    CONTINENTAL STOCK TRANSFER & TRUST COMPANY, AS WARRANT
AGENT

	 	 	 
	 	By:	 
	 	 	Name:	 
	 	 	Title:	 

 

 

[Signature Page to Warrant Certificate]

 

    2

     

    

 

[Form of Warrant Certificate] 

 

[Reverse] 

 

The Warrants evidenced by this Warrant Certificate are part of a duly
authorized issue of Warrants entitling the holder on exercise to receive Ordinary Shares and are issued or to be issued pursuant to a
Warrant Agreement dated as of [__], 2021 (the “Warrant Agreement”), duly executed and delivered by the Company
to Continental Stock Transfer & Trust Company, a New York corporation, as warrant agent (the “Warrant Agent”),
which Warrant Agreement is hereby incorporated by reference in and made a part of this instrument and is hereby referred to for a description
of the rights, limitation of rights, obligations, duties and immunities thereunder of the Warrant Agent, the Company and the holders (the
words “holders” or “holder” meaning the Registered Holders or Registered Holder, respectively)
of the Warrants. A copy of the Warrant Agreement may be obtained by the holder hereof upon written request to the Company. Defined terms
used in this Warrant Certificate but not defined herein shall have the meanings given to them in the Warrant Agreement.

 

Warrants may be exercised at any time during the Exercise Period set
forth in the Warrant Agreement. The holder of Warrants evidenced by this Warrant Certificate may exercise them by surrendering this Warrant
Certificate, with the form of Election to Purchase set forth hereon properly completed and executed, together with payment of the Exercise
Price as specified in the Warrant Agreement (or through “cashless exercise” as provided for in the Warrant Agreement)
at the principal corporate trust office of the Warrant Agent. In the event that upon any exercise of Warrants evidenced hereby the number
of Warrants exercised shall be less than the total number of Warrants evidenced hereby, there shall be issued to the holder hereof or
his, her or its assignee, a new Warrant Certificate evidencing the number of Warrants not exercised.

 

Notwithstanding anything else in this Warrant Certificate or the Warrant
Agreement, no Warrant may be exercised unless at the time of exercise (i) a registration statement covering the issuance of the Ordinary
Shares to be issued upon exercise is effective under the Securities Act and (ii) a prospectus thereunder relating to the Ordinary Shares
is current, except through “cashless exercise” as provided for in the Warrant Agreement.

 

The Warrant Agreement provides that upon the occurrence of certain
events the number of Ordinary Shares issuable upon exercise of the Warrants set forth on the face hereof may, subject to certain conditions,
be adjusted. If, upon exercise of a Warrant, the holder thereof would be entitled to receive a fractional interest in an Ordinary Share,
the Company shall, upon exercise, round down to the nearest whole number of Ordinary Shares to be issued to the holder of the Warrant.

 

Warrant Certificates, when surrendered at the principal corporate trust
office of the Warrant Agent by the Registered Holder thereof in person or by legal representative or attorney duly authorized in writing,
may be exchanged, in the manner and subject to the limitations provided in the Warrant Agreement, but without payment of any service charge,
for another Warrant Certificate or Warrant Certificates of like tenor evidencing in the aggregate a like number of Warrants.

 

Upon due presentation for registration of transfer of this Warrant
Certificate at the office of the Warrant Agent a new Warrant Certificate or Warrant Certificates of like tenor and evidencing in the aggregate
a like number of Warrants shall be issued to the transferee(s) in exchange for this Warrant Certificate, subject to the limitations provided
in the Warrant Agreement, without charge except for any tax or other governmental charge imposed in connection therewith.

 

The Company and the Warrant Agent may deem and treat the Registered
Holder(s) hereof as the absolute owner(s) of this Warrant Certificate (notwithstanding any notation of ownership or other writing hereon
made by anyone), for the purpose of any exercise hereof, of any distribution to the holder(s) hereof, and for all other purposes, and
neither the Company nor the Warrant Agent shall be affected by any notice to the contrary. Neither the Warrants nor this Warrant Certificate
entitles any holder hereof to any rights of a shareholder of the Company.

 

    3

     

    

 

Election to Purchase

 

(To Be Executed Upon Exercise of Warrant)

 

The undersigned hereby irrevocably elects to exercise the right, represented
by this Warrant Certificate, to receive Ordinary Shares and herewith tenders payment for such Ordinary Shares to the order of ONS Acquisition
Corp. (the “Company”) in the amount of $ in accordance with the terms hereof. The undersigned requests that
a certificate for such Ordinary Shares be registered in the name of , whose address is and that such Ordinary Shares be delivered to whose
address is . If said number of Ordinary Shares is less than all of the Ordinary Shares purchasable hereunder, the undersigned requests
that a new Warrant Certificate representing the remaining balance of such Ordinary Shares be registered in the name of , whose address
is and that such Warrant Certificate be delivered to , whose address is .

 

In the event that the Warrant is a Private Placement Warrant that is
to be exercised on a “cashless” basis pursuant to subsection 3.3.1(c) of the Warrant Agreement, the number of Ordinary
Shares that this Warrant is exercisable for shall be determined in accordance with subsection 3.3.1(c) of the Warrant Agreement.

 

In the event that the Warrant is to be exercised on a “cashless”
basis pursuant to Section 7.4 of the Warrant Agreement, the number of Ordinary Shares that this Warrant is exercisable for shall
be determined in accordance with Section 7.4 of the Warrant Agreement.

 

In the event that the Warrant may be exercised, to the extent allowed
by the Warrant Agreement, through cashless exercise (i) the number of Ordinary Shares that this Warrant is exercisable for would be determined
in accordance with the relevant section of the Warrant Agreement which allows for such cashless exercise and (ii) the holder hereof shall
complete the following: The undersigned hereby irrevocably elects to exercise the right, represented by this Warrant Certificate, through
the cashless exercise provisions of the Warrant Agreement, to receive Ordinary Shares. If said number of shares is less than all of the
Ordinary Shares purchasable hereunder (after giving effect to the cashless exercise), the undersigned requests that a new Warrant Certificate
representing the remaining balance of such Ordinary Shares be registered in the name of , whose address is and that such Warrant Certificate
be delivered to , whose address is .

 

[Signature Page Follows]

 

    4

     

    

 

Date:      , 2021

 

	 	 	 
	 	 	(Signature)
	 	 	 
	 	 	(Address)
	 	 	 
	 	 	 
	 	 	(Tax Identification Number)
	 	 	 
	Signature Guaranteed:	 	 
	 	 	 

 

THE SIGNATURE(S) SHOULD 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).

 

5

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