San Diego (Exposition Sta)., Cal./Registered. Rare violet double circle (Bomar SD15-) backstamp on 1915 registered cover to Ohio, franked with 1¢ + 2¢ Pan-Pacific in combination 5¢ Jamestown + 4¢ Parcel Post tied by San Diego oval cancels, included is the original registered receipt filled out in pencil denoting the Expo. Station, cover opened for display, Very Fine. Estimate  $500 - 750. $0 (Image)