Gearbelt Pulley Bore Diameter 1/2 in For Belt Series SilentSync For Belt Width 25 mm For Use With 25 mm Belt Material Aluminum Maximum Bore Diameter 2 7/16 in Number of Teeth 40 Outside Diameter 3.969 in Pitch 8 mm Pitch Diameter 4.01 in Bore Type Plain Face Width 26 mm For Belt Trade Size SilentSync Hub Diameter 3 5/8 in Hub Projection 5/8 in Hub Type One Side Keyway No Keyway Depth Not Applicable Keyway Width Not Applicable Length through Bore 1 21/32 in