50 Heller exhibition Kaschau with inverted hand stamp overprint "Karlovy Vary 1. X. 1938 plus swastika", with cancellation adjusted date stamp Karlovy Vary 1 4. X. 38 on faultless letter piece, edition 452 examples, of it the fewest with inverted overprint, expertized Dr. Dub, photo expertize Brunel VP (2021) "the condition is perfect. the stamp with inverted overprint is very rare. ", Michel 3.000.-