Sprocket Bore Diameter 1 7/16 in For Chain Pitch 3/4 in For Number of Strands Single Hub Type One Side Material Steel Maximum Bore Diameter 1 7/16 in Number of Teeth 21 Outside Diameter 5.43 in Pitch Diameter 5.033 in Bore Type Fixed Chain Number 60 Finish Black Oxide Hub Diameter 4 in Hub Projection 0.791 in Includes Set Screws Keyway Yes Keyway Depth 3/16 in Keyway Width 3/8 in Length through Bore 1 1/4 in Number of Set Screws 2