At the time of writing this was one of two known adjustable Injectors.
It was introduced in June 1962 and was the first. At the time it was advertised as "the only adjustable injector razor". Its a simplistic one-piece design but still looks super slick and very "Mod".
The adjustment dial functions fine, but I find it a bit small and as a result, I tend to pick a setting and leave it there for the whole shave