50 C. Special stamp \"Congres you B. I. T. \", horizontal pair, with hand stamp overprint in type I, as properly franked multiple franking on cover from \"Ghyvelde north 2-8-40\", to Dunkerque north with arrival postmark on the back from 3-8-40, faultless condition, signed Dreyfus, Roumet, Tust BPP and expertise Lothar Herbst VP (2018) : \"the condition is perfect. \"