Dating codes gillette razors
Rarer than the Fatboy we commonly see today, there was the Bottom Dial.
Gillette built a very small number of prototypes as per the patent drawing. This patent says: “This results flows from the fact that the relative positions of the guard member is controlled by the adjusting knob”. The “Red Dot” (so dubbed for the red dot to mark the adjustment setting) was one of several prototypes built by Gillette back in the 1950’s when they were developing the 195 adjustable razor that we affectionately refer to as the “Fat Boy”.