20 C. Merkur head, 30 C. Merkur head and 50 C. Special stamp \"BIT 1930 Conference of the international Bureau of Labor\" with joint overprint \"Occupied area North France\" in type I as properly franked mixed franking on small-format ladies letter from \"Dunkerque 16.07.1940\" to Ghyvelde with arrival postmark on the back from 17.07.1940, faultless condition, expertized Roumet among others as well expertise Lothar Herbst VP (2023) \"the condition is perfect. The stamps are only in very small number of pieces known, therefore are they very rare. \", Michel 1.500.-