15 C. Postal stamp "Merkur head" and 85 C. Airmail issue 1936 "airplane over Paris" with overprint in type I, properly franked mixed franking on letter from "Dunkerque 11.07.1940" to Ghyvelde with reverse arrival postmark from "12.07.1940", faultless condition, expertise Lothar Herbst VP (2019: "the condition is perfect. The stamps are only in very small number of pieces known, therefore are they very rare. ", Michel 1.500.-