Roller Chain Sprocket, Bore Diameter 3/4 in, For Chain Pitch 1/2 in, For Number of Strands Double, Hub Type One Side, Material Steel, Maximum Bore Diameter 3/4 in, Number of Teeth 12, Outside Diameter 2.17 in, Pitch Diameter 1.932 in, Bore Type Fixed, Chain Number 40-2, Finish Black Oxide, Hub Diameter 1 9/16 in, Hub Projection 0.659 in, Includes Set Screws, Keyway Yes, Keyway Width 3/16 in, Length through Bore 1 1/2 in