Roller Chain Sprocket Bore Diameter 30 mm For Chain Pitch 3/4 in For Number of Strands Single Hub Type One Side Material Steel Maximum Bore Diameter 30 mm Number of Teeth 25 Outside Diameter 6.45 in Pitch Diameter 151.99 mm Bore Type Fixed Chain Number 12B Finish Black Oxide Hub Diameter 100 mm Hub Projection 1.137 in Includes Set Screws Keyway Yes Keyway Width 8 mm Length through Bore 40 mm Number of Set Screws 2