70 C. Merkur head and 30 C. Special edition \"world exhibition 1937 in Paris\" with overprint in type I, properly franking on cover from \"Ghyvelde 21.07.1940\" to Dunkerque with arrival cancel from 22.07.1940, faultless condition, expertized Behr and 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 900.-