2010 Pennsylvania Code
Title 13 - COMMERCIAL CODE
Chapter 22 - Form, Formation and Readjustment of Contract
2205 - Firm offers.

     § 2205.  Firm offers.
        An offer by a merchant to buy or sell goods in a signed
     writing which by its terms gives assurance that it will be held
     open is not revocable, for lack of consideration, during the
     time stated or if no time is stated for a reasonable time, but
     in no event may such period of irrevocability exceed three
     months; but any such term of assurance on a form supplied by the
     offeree must be separately signed by the offeror.