Up for auction is a beautiful airmail cover mailed and flown on the Graf Zeppelin from New York City to Detroit Michigan USA on the Graf Zeppelin First round trip Pan American Flight. Priced to sell. Postmarked April 30, 1930.  Cover is in Good condition. Very nice zeppelin  cover and great US franking and markings. Block of four Airmail stamp # C13 on cover with a 2018 value of $165 for each used stamp alone $660 for all four.