Sprocket Bore Diameter 5/8 in For Chain Pitch 1/2 in For Number of Strands Single Hub Type One Side Material Steel Maximum Bore Diameter 1 7/8 in Number of Teeth 21 Outside Diameter 3.62 in Pitch Diameter 3.355 in Bore Type Plain Chain Number 40 Finish Black Oxide Hub Diameter 2 3/4 in Hub Projection 0.716 in Keyway No Keyway Depth Not Applicable Keyway Width Not Applicable Length through Bore 1 in Number of Set Screws 0 Set Screw Location Not Applicable