N.Y. Gen. Oblig. Law § 5-1109

§ 5-1109. Written irrevocable offer. Except as otherwise provided in\nsection 2-205 of the uniform commercial code with respect to an offer by\na merchant to buy or sell goods, when an offer to enter into a contract\nis made in a writing signed by the offeror, or by his agent, which\nstates that the offer is irrevocable during a period set forth or until\na time fixed, the offer shall not be revocable during such period or\nuntil such time because of the absence of consideration for the\nassurance of irrevocability. When such a writing states that the offer\nis irrevocable but does not state any period or time of irrevocability,\nit shall be construed to state that the offer is irrevocable for a\nreasonable time.\n