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 3.000.- (former starting price 1000)