A genuine unused block of four, original gum, never hinged; as noted on accompaning certifications the top stamps are SC 511 (perf 11), the bottom left stamp has transitional perf 11/10 on bottom, and bottom right stamp is perf 10 (SC# 511a). Very high catalog value--make a fair offer and add this excellent block to your collection. Are you a New York city or state resident? The item "SC# 511a OG MNH BLOCK OF 4, 11c, 1917, TOP TWO 511 PERF 11, 3 PSE CERTS, HIGH CV" is in sale since Monday, March 25, 2019. This item is in the category "Stamps\United States\1901-40\ Unused".The seller is "uscprestigepostal" and is located in Queensbury, New York. This item can be shipped to United States.