25 C. Mercury blue-green as a block of four with two vertically overprinted pairs as a valid 1 Fr. postage on a letter from "Dunkerque 2. 8. 40" to Malo les Bains with arrival postmark dated 3. 8. 40, envelope with traces of handling, stamps in flawless condition, signed Roumet and expertise by Lothar Herbst VP (2025) "The condition of the stamps is impeccable. The stamps were issued in a very small edition of only 800 pairs.", Michel 2. 100.-