50 C. Charity issue "Musica with new overprint + 20 C." with overprint in Type I, vertical pair with the variety "inverted overprint", proper multiple franking on a letter from Ghyvelde on July 11, 1940 to Dunkirk with a backstamped arrival postmark dated July 12, 1940, flawless condition, certified by Calves, Dreyfus, Roumet and expertise by Lothar Herbst VP (2025) "The condition is impeccable. The stamps are known in very small quantities, therefore they are very rare. Multiple frankings with charity stamps, especially with inverted overprint, are extremely rare.", Michel 1. 700.-