Worldwide Pioneer Flights - Afghanistan

Worldwide Pioneer Flights - Afghanistan

1939, Airplane over Kabul, 20af emerald, bottom sheet margin horizontal imperforated pair (issued in 1949) and small die proof of the same value in slightly different color (bright bluish green), printed on vertically wove paper, size 37.5x20.5mm instead of 39x21mm for issued stamps, full OG, NH (imperf pair) or LH, VF, these proofs are rarely offered, Est. $100-$150, Sc. #C3a