50 Heller stamp exhibition Pilsen" with dark pink red hand stamp overprint "Karlovy Vary 1. X. 1938+swastika", variety "inverted overprint", tied by cancellation adjusted date stamp "Karlovy Vary 1 4. X. 38 4 b" on letter piece, expertized Dr. Dub (double signature) and expertise Brunel VP (2021) : "the condition is perfect. The stamp with inverted overprint is very rare. ", Michel used unknown! For * already 2.500.-!