Home / Stamps / Australia & Territories / George V / Airmail overprinted OS Airmail overprinted OSPrice: $25.00 1931 Airmail overprinted OS. SG 139a. Mint Unhinged Out of stock SKU: 100730 Categories: George V, Stamps Specifications Value Appraisal Product Features Additional Products 6d Kookaburra $40.00 BUY NOW 3d Kookaburra $8.00 BUY NOW 3d Kookaburra $3.50 BUY NOW National Stamp Exhibition, Melbourne $6.00 BUY NOW