Roller Chain Sprocket Bore Diameter 28 mm For Chain Pitch 1 1/4 in For Number of Strands Single Hub Type One Side Material Steel Maximum Bore Diameter 28 mm Number of Teeth 11 Outside Diameter 5.1 in Pitch Diameter 112.7 mm Bore Type Fixed Chain Number 20B Finish Black Oxide Hub Diameter 79 mm Hub Projection 1.157 in Includes Set Screws Keyway Yes Keyway Width 8 mm Length through Bore 48 mm Number of Set Screws 2