This is the same sprocket that guides #25 chain and drive sprocket. The sprocket has 20 teeth with a .25" pitch and contains an R6 ball bearing with a 3/8" ID (inside diameter).
You can use this mechanism to either help position the roller chain to assist the drive sprocket, or be used as a free wheel for one end of a loop of roller chain. This sprocket has a 5/8" inside diameter and 17 teeth and can be sold with the 5/8" bolt and nut if desired.
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