10 C. Postal stamp "Merkur head and 90 C. Postal stamp "peace allegory" with overprint in type I, correctly franked mixed franking on letter from "Dunkerque 18.07.1940" to Ghyvelde with reverse arrival postmark from "19.07.1940", faultless condition, 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 800.-