Gearbelt Pulley Bore Diameter 1/2 in For Belt Series SilentSync For Belt Width 50 mm For Use With 50 mm Belt Material Aluminum Maximum Bore Diameter 1 5/8 in Number of Teeth 28 Outside Diameter 2.75 in Pitch 8 mm Pitch Diameter 2.807 in Bore Type Plain Face Width 51 mm For Belt Trade Size SilentSync Hub Diameter 2 7/16 in Hub Projection 5/8 in Hub Type One Side Keyway No Keyway Depth Not Applicable Keyway Width Not Applicable Length through Bore 2 21/32 in