1949 Airmail cover from a Swedish Missionary in Wuchang, Hupeh, China to Lindingö in Sweden bearing a block of 12 $500.000 on $20 red and a strip of four $100.000 on $20. Covers with multiples of $100,000 on $20 stamps are rare. Covers with any $500,000 on $20 stamps are very rare. A cover with a block of 12 of these stamps is in all probability unique! (Image)