The FR-4 is made from heat treated alloy tool steel, one inch base fits wrench or bench vice.
One-inch base fits end of SR-1, FRW-1 Park tools or simply an adjustable wrench / spanner or bench vice
Fits Atom, Regina, Zeus and Schwinn notch freewheels with 22mm inside diameter
Note: You will also need a chain whip tool to hold the cog in place.
Weight: 58g (2.ozs)
Park Tool Reference: FR-4
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