50 cent charity issue \"Musica\" with hand stamp overprint in type I, variety \"inverted overprint\", properly franked multiple franking on cover from Ghyvelde 10.07.1940 to Dunkerque with on the back arrival stamp from 11.07.1940, expertise Lothar Herbst VP (2018) : \"the condition is perfect. The stamps are general only in very small number of pieces known, therefore are they very rare. Multiple franking with charity stamps, to boot with inverted overprint, are extremely rare. \", Michel 2.100.-