Roller Chain Sprocket, Bore Diameter 3/4 in, For Chain Pitch 1/2 in, For Number of Strands Single, Hub Type One Side, Material Steel, Maximum Bore Diameter 3/4 in, Number of Teeth 18, Outside Diameter 3.14 in, Pitch Diameter 2.879 in, Bore Type Fixed, Chain Number 41, Finish Black Oxide, Hub Diameter 2 3/8 in, Hub Projection 0.773 in, Includes Set Screws, Keyway Yes, Keyway Width 3/16 in, Length through Bore 1 in, Number of Set Screws 2