This is a brand new rear plunger frame top (heavier) spring . Sold as each.
Fits: All BSA M20, M21, B31, B32, B33, B34, A7, A10 and Goldstar with plunger frame.
Part number: 67-4132
Total length: 6 1/4″
Outside diameter: 1 3/4″
Thickness of coil: 0.25″ (7mm)