25 C. Postal stamp "Merkur head" with overprint in type I, common, horizontal over all fours stamps walking overprint, correctly franked more franking on letter from "Ghyvelde 29.07.1940" to Dunkerque with reverse arrival postmark from "30.07.1940", faultless condition, expertise Lothar Herbst VP (2018) : "the condition is perfect. The stamps are only in very small number of pieces known, therefore are they very rare. ", Michel 1.000.-