I believe that this is a flyer handed out at a French trade show in 1949. Points of note include:
- The emphasis on the rigidity of the mechanism. Simplex derailleurs of the time had a reputation for fragility.
- The mention of the sealed body and rubber boot that covered the sliding rod. Again the exposed mechanisms of other contemporary derailleurs was seen as a fatal weakness by many - particularly those who advocated hub gears.
- The address in Malakoff, a southern suburb of Paris.