1921, 1¢ green, rotary coil waste, imperf between, block of six with two pairs at left showing the error and two stamps at right normal, rich color, top pair with internal crease, o.g., lightly hinged, otherwise Very Fine and rare multiple; with 1978 and 1997 P.F. certificates. Scott No. 543a  $10,000 as two pairs. THE ONLY RECORDED IMPERF BETWEEN BLOCK THAT CONTAINS TWO OF THE LESS THAN 10 RECORDED IMPERF BETWEEN HORIZONTAL PAIRS. We recorded only one other imperf between error block (ex-Whitman, Sirron) that was subsequently broken into two pairs after being auctioned in 2010. This is now the unique block. $0 (Image)