San Francisco, Cal / M.P.O., three strikes of double-oval cancel tie 2¢ and 5¢ Pan-Pacific (398, 399) and 5¢ Jamestown (330) on 1915 registered cover to Cleveland, Oh., reverse with scarce purple "San Francisco (Model Post Office Sta.) Cal., Registered, Mar 29 1915" double-circle backstamps (Bomar SF-15-06) backstamps, purple Cleveland (4.2) arrival cds; cover opened for display, Very Fine and attractive. Bomar Nos. SF15-05A  Estimate $750 - 1,000. ONE OF ONLY FIVE RECORDED EXAMPLES OF THIS RARE "M.P.O." CANCELLATION USED FROM THE EXPOSITION, THE ONLY RECORDED EXAMPLE ON A REGISTERED COVER. In addition to this full cover, four other examples of this cancel are known. One used as a back stamp on a cover mailed from the Model Post Office, another as a favor cancel on post card along with Bomar SF15-01, an undated package label mailed from the Exposition company office, and the last is on an undated cover used as a parcel label from the Japanese Tourist Bureau to mail exposition promotional material. $0 (Image)