A great pair of postal covers flown on the airship 'Graf Zeppelin', the first a Sieger 238Bab 'Century of Progress' commemorative cover flown on the Oct. 16, 1933 Friedrichshaffen-America flight, with red 'Luftschiff Graf Zeppelin Sudamerikafahrt' round trip cachet on recto and ‘Air-Mail Saves Time’ stamp on verso. Along with a Sieger 241G cover flown on the Germany-American flight Oct. 2, 1933, with red 'Luftschiff Graf Zeppelin 50. Ozeanüberquerung Sudamerikafahrt' round trip and purple 'Graf Zeppelin Flight Century of Progress Exposition' cachets. Two pieces, very good.