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 2 1/4 in Number of Teeth 25 Outside Diameter 4.26 in Pitch Diameter 3.989 in Bore Type Plain Chain Number 40 Finish Black Oxide For Pitch Type Single Pitch Hub Diameter 3 1/4 in Hub Projection 0.716 in Includes Set Screws Keyway Yes Keyway Depth 3/32 in Keyway Width 3/16 in Length through Bore 1 in Material Grade 1045