Bidspirit auction | United States - Modern Errors

United States - Modern Errors and Varieties - 1993, Classic Books, 29c multicolored, proof pane of 40 stamps, containing ten se-tenant blocks or strips of four, perforated horizontally at top and vertically between stamps of the upper row only, imperforate everywhere else, full OG, NH, VF, C.v. $4,000 as eight blocks and two strips, Est. $1,500-$2,000, Scott #2788a P