Suits to the timing belt which is 6mm/0.24" width.Teeth: 40T; Bore: 8mm/0.31"; Total Size: 27.5x27.5x17mm/1.08"x1.08"x0.67"(L*W*H) 40 contact with the tooth side which minimizes the risk of the belt slipping Adopting high quality Aluminum Alloy material，sturdy and durable,surface oxidation treatment, anti-Rust and Anti-corrosion effectively