Mid-Winter Fair Sta., S.F., Cal. Numeral "3" Duplex Cancel. (Bomar SF94-02) on 2¢ Columbian Postal entire with all over Expo design & corner card of the "Offices of the Executive Committee", Very Fine, a wonderful cover of which only three examples of this rare postmark are known. Estimate  $500 - 750. $0 (Image)