Roller Chain Sprocket Bore Diameter 1 1/4 in For Chain Pitch 1 in For Number of Strands Single Hub Type One Side Material Steel Maximum Bore Diameter 1 1/4 in Number of Teeth 28 Outside Diameter 9.48 in Pitch Diameter 8.931 in Bore Type Fixed Chain Number 80 Finish Black Oxide Hub Diameter 4 3/4 in Hub Projection 1.425 in Includes Set Screws Keyway Yes Keyway Width 1/4 in Length through Bore 2 in Number of Set Screws 2