Vintage and extremely rare 1958 Sturmey Archer four speed medium ratio (FM) hub gear in excellent condition with chrome steel shell. 40 hole shell. Shell is very clean, and is the first steel shell FM hub I've seen. Spoke holes and flanges are in near perfect condition.
The FM ratios are -33.33%, -14.3%, direct, and +12.5%. These gears were made from 1936 - 1963, this unit is February 1958.