Bidspirit auction | Worldwide Air Post Stamps and

Worldwide Air Post Stamps and Postal History - Czechoslovakia - 1920, First Air Post issue, six proofs of Airplane surcharges on blank pieces, black and red of 14k on white paper, black of 24k on cream paper, two black and one green of 28k, two on white and one on cream paper, no gum as issued, VF and rare, two with experts' hs on reverse, Est. $250-$300, Scott #C1-3