cover 1931, 4m Polar Flight (C42, Michel 458), very fine centered single tied by Friedrichshafen c.d.s. on Zeppelin Polar Flight cover to the U.S. (Sieger 119C), with overall printed cover cachet in green, Ice Breaker Malyguin and red flight cachets, purple Malyguin backstamp, stamp has minor corner perf. crease, otherwise very fine