50 C. Postal stamp \"Merkur head\" with overprint in type I, horizontal pair with overprint, properly franked more franking on cover from \"Ghyvelde 2.08.1940\" to Dunkerque with reverse arrival postmark from \"3.08.1940\", faultless preservation, expertise Lothar Herbst VP (2018) : \"the preservation is perfect. The stamps are only in very small number of pieces known, therefore are they rare, Michel 400.-