Bidspirit auction | Soviet Union Stamps of 1924-40

Soviet Union Stamps of 1924-40 - 1938, Papanin's North Pole Expedition, 50k ultra, horizontal imperforated pair with nice margins, which are enlarged at top and bottom, full OG, two light traces of hinge, VF and very scarce, C.v. $2,350, Est. $1,000-$1,500 , Sc. #646a