1c Green, Perf 11 x 10-1/2, Vertical Pair, Imperforate Between (632b). Mint N.H., deep rich color on bright paper, wide margins
According to Gary Griffith, this error was discovered in 1939 in Bergen N.Y. The find was reported as thirteen blocks of four and three pairs, but some were subsequently determined to have blind perfs and were disqualified.
Illustrated in United States Stamps 1927-32 by Gary Griffith and from his collection. Ex Floyd. With 1996 P.F. certificate