Exhibit 4.3


 


Form of Warrant Certificate


 


[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


 


B. RILEY
PRINCIPAL MERGER CORP.


 


Incorporated Under the Laws of the State
of Delaware


 


CUSIP 05586Y 114


 


Warrant Certificate


 


This Warrant
Certificate certifies that           , or registered assigns, is the
registered holder of warrant(s) evidenced hereby (the “Warrants” and each, a “Warrant”)
to purchase shares of Class A common stock, $0.0001 par value per share (“Class A Common Stock”), of
B. Riley Principal Merger Corp., a Delaware corporation (the “Company”). Each whole Warrant entitles
the holder, upon exercise during the Exercise Period set forth in the Warrant Agreement referred to below, to receive from the
Company that number of fully paid and non-assessable shares of Class A Common Stock as set forth below, at the exercise price (the
“Warrant 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 Warrant 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 share of Class A Common Stock. No fractional shares will be issued
upon exercise of any Warrant. If, upon the exercise of Warrants, a holder would be entitled to receive a fractional interest in
a share of Class A Common Stock, the Company will, upon exercise, round down to the nearest whole number the number of shares of
Class A Common Stock to be issued to the Warrant holder. The number of shares of Class A Common Stock 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 Warrant
Price per share of Class A Common Stock for any Warrant is equal to $11.50 per share. The Warrant Price is subject to adjustment
upon the occurrence of certain events 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.


 


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, without regard to conflicts of
laws principles thereof.


 


	 	B. RILEY PRINCIPAL MERGER CORP.
	 	 	 
	 	By:	            
	 	Name:	 
	 	Title:  	 
	 	 	 
	 	CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Warrant Agent
	 	 	 
	 	By:	 
	 	Name:	 
	 	Title:  	 


 




     


     


    

 


[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 shares
of Class A Common Stock and are issued or to be issued pursuant to a Warrant Agreement dated as of            ,
2019 (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 Warrant 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 shares of Class A Common Stock to be issued upon exercise is effective under the Securities Act and (ii)
a prospectus thereunder relating to the shares of Class A Common Stock 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 shares of Class A Common Stock issuable upon the exercise of
the Warrants set forth on the face hereof may, subject to certain conditions, be adjusted.


 


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 stockholder of
the Company.


 




     


     


    

 


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               
shares of Class A Common Stock and herewith tenders payment for such shares of Class A Common Stock to the order of B. Riley Principal
Merger Corp. (the “Company”) in the amount of $        in accordance with
the terms hereof. The undersigned requests that a certificate for such shares of Class A Common Stock be registered in the name
of            , whose address is            
and that such shares of Class A Common Stock be delivered to                   
whose address is           . If said number of shares of Class A Common Stock
is less than all of the shares of Class A Common Stock purchasable hereunder, the undersigned requests that a new Warrant Certificate
representing the remaining balance of such shares of Class A Common Stock 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 has been called for redemption by the Company pursuant to Section 6 of the Warrant Agreement and the Company has
required cashless exercise pursuant to Section 6.3 of the Warrant Agreement, the number of shares of Class A Common Stock
that this Warrant is exercisable for shall be determined in accordance with subsection 3.3.1(b) and Section 6.3 of
the Warrant Agreement.


 


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 shares of Class A Common Stock 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 shares of Class A Common Stock 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 shares of
Class A Common Stock 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 shares of Class A Common Stock. If said number of shares of Class A Common Stock is less than
all of the shares of Class A Common Stock purchasable hereunder (after giving effect to the cashless exercise), the undersigned
requests that a new Warrant Certificate representing the remaining balance of such shares of Class A Common Stock be registered
in the name of             , whose address is                  
and that such Warrant Certificate be delivered to             , whose
address is              .


 


[Signature Page Follows]


 




     


     


    

 


	Date:            , 20	 	 
	 	 	(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 SEC RULE 17Ad-15 UNDER THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED (OR ANY
SUCCESSOR RULE).