1917, 1¢ green, block of fifteen, straight edge at bottom, tied by "Registered, Shanghai, China" ovals on reverse of registered cover from Shanghai, China to Vienna, Austria, purple "U.S. Postal Agency (Shanghai, China) Apr 10, 1920" cds on front and back, block also tied by New York Registered transit oval; cover tear on front and back, Fine, The largest recorded usage on cover. Scott No. 498  Estimate $300 - 400. $0 (Image)