PCGT Timing Belt Pulley Bore Diameter 1/2 in For Belt Series Poly Chain GT Carbon For Belt Width 21 mm For Use With Poly Chain(R) GT(R) Carbon belts Material Steel Maximum Bore Diameter Not Applicable Number of Teeth 25 Outside Diameter 2.953 in Pitch 8 mm Pitch Diameter 2.506 in Bore Type Plain Face Width 1.203 in Features Built for High-Torque Low-Speed Applications Outperforms Industry Standards Superb Flexibility Finish Black Oxide For Belt Trade Size Carbon