10 C. Postage stamps issue "Merkur head" and 90 cent charity issue "unemployed children" with hand stamp overprint in type I, correctly franked mixed franking on cover from "Dunkerque 06.07.40" to Ghyvelde with on the back arrival stamp from 074.07.1940, faultless condition, unsigned, 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.-