1930 Graf Zeppelin stamps

The 1930 Graf Zeppelin stamps were a set of three airmail postage stamps, each depicting the image of the Graf Zeppelin, issued by the United States Post Office Department in 1930, exclusively for delivery of mail carried aboard that airship. Although the stamps were valid for postage on mail sent on the Zeppelin Pan American flight from Germany to the United States, via Brazil, the set was marketed to collectors and was largely intended to promote the route.

Source: Wikipedia — 1930 Graf Zeppelin stamps (CC BY-SA 4.0)