Elite, 'narrow' rear chain, from gearbox sprocket to rear wheel.
Chain size: 520 | 5/8x1/4 | 110-054
Number of links: 110
Includes spring link.
For example for:
BSA: M20, M21, B25, B31, B32, B44, M33,
B33 rigid plunger frame. B34 up to 1955, B50
Norton: 16H, model 18, E.S.2 up to 1963, Dominator up to 1964