25 C. Postal stamp "Merkur head" with overprint in type I, vertical strip of four - overprint in pairs over two stamps, correctly franked more franking on cover from "Ghyvelde 1.08.1940" to Dunkerque with reverse arrival postmark from "2.08.1940", 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.-