N.Y. UCC Law § 2-207

Section 2--207. Additional Terms in Acceptance or Confirmation.\n (1) A definite and seasonable expression of acceptance or a written\nconfirmation which is sent within a reasonable time operates as an\nacceptance even though it states terms additional to or different from\nthose offered or agreed upon, unless acceptance is expressly made\nconditional on assent to the additional or different terms.\n (2) The additional terms are to be construed as proposals for addition\nto the contract. Between merchants such terms become part of the\ncontract unless:\n (a) the offer expressly limits acceptance to the terms of the\n offer;\n (b) they materially alter it; or\n (c) notification of objection to them has already been given or\n is given within a reasonable time after notice of them is\n received.\n (3) Conduct by both parties which recognizes the existence of a\ncontract is sufficient to establish a contract for sale although the\nwritings of the parties do not otherwise establish a contract. In such\ncase the terms of the particular contract consist of those terms on\nwhich the writings of the parties agree, together with any supplementary\nterms incorporated under any other provisions of this Act.\n