Specimen Unit Certificate

Exhibit 4.1

SPECIMEN UNIT CERTIFICATE

U-

CUSIP [    ]

UNITS CONSISTING OF ONE CLASS A ORDINARY SHARE AND ONE-THIRD OF ONE REDEEMABLE WARRANT EACH WHOLE REDEEMABLE WARRANT TO PURCHASE ONE CLASS A ORDINARY SHARE

THIS CERTIFIES THAT                                                                                                                                                 is the owner of                                                                                                                Units.

Each Unit (“Unit”) consists of one (1) Class A ordinary share, par value $0.0001 per share (“Class A ordinary share(s)”), of Iron Horse Acquisition Corp., a Cayman Islands exempted company (the “Company”), and one-third of one redeemable warrant (the “Warrant(s)”). Each whole Warrant entitles the holder to purchase one (1) Class A ordinary share for $11.50 per share (subject to adjustment). Each Warrant will become exercisable on the later of (i) 30 days after the Company’s completion of a merger, share exchange, asset acquisition, share purchase, reorganization or other similar business combination (“Business Combination”) and (ii) 12 months from the closing of the Company’s initial public offering (“IPO”), and will expire unless exercised before 5:00 p.m., New York City Time, on the fifth anniversary of the completion of an initial Business Combination, or earlier upon redemption or the Company’s liquidation (the “Expiration Date”). The Class A ordinary shares and Warrants comprising the Units represented by this certificate are not transferable separately prior to the 52nd day after the date of the prospectus relating to the Company’s IPO, subject to earlier separation in the discretion of Citigroup Global Markets Inc. and Goldman Sachs & Co. LLC provided that the Company has filed with the Securities and Exchange Commission a Current Report on Form 8-K which includes an audited balance sheet reflecting the Company’s receipt of the gross proceeds of the IPO and issued a press release announcing when separate trading will begin. The terms of the Warrants are governed by a Warrant Agreement, dated as of                     , 2018, between the Company and Continental 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 17 Battery Place, New York, New York 10004, 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.

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

Iron Horse Acquisition Corp.

The Company will furnish without charge to each shareholder who so requests, a statement of 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.

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:

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

For value received, hereby sell, assign and transfer unto

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

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

Dated                     

Signature(s) 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).

The holder(s) of this certificate shall be entitled to receive a pro-rata portion of the funds from the trust account with respect to the ordinary shares underlying this certificate only in the event that (i) the Company is forced to liquidate 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 (the “Charter”) or (ii) if the holder seeks to convert his shares upon consummation of, or sell his shares in a tender offer in connection with, an initial business combination or in connection with certain amendments to the Charter. In no other circumstances shall the holder(s) have any right or interest of any kind in or to the trust account.