25 C. Postal stamp "Merkur head" and 75 C. Postal stamp "Paul Doumer" with overprint in type I, properly franked mixed franking on cover from Ghyvelde 21.07.1940 to Dunkerque with on the back arrival stamp from 22.07.1940, faultless condition, expertise Lothar Herbst VP (2019) : "the condition is perfect. The stamps are only in very small number of pieces known, therefore are they very rare. ", Michel 1.700.-