2 Reichmark South America flight with watermark upright in mixed franking with 4 Reichmark South America flight (2 values) with watermark sideways, on airmail international letter to the United States, transported with airship Graff Zeppelin, red special confirmation postmark \"airship Count Zeppelin South America flight 1930\", reverse green special confirmation postmark \"Count Zeppelin Pan America Round Flight Lakehurst 31.5.30\", the letter is 2 Reichmark overfranked, the franking in perfect condition, the cover is age-related brownish blotched, photo expertize H. D. Schlegel BPP (2022), Michel for single stamp stamps 1.500.-