Material: 45# metallic (surface blackening)Colour: blackStandard / non-standard: standardTooth surface hardness: softPitch: 0.5 modNumber of Teeth: 30TBore Diameter: 5-10mmTotal Height: about 10mmWith / Without Set Screws: with set screws (2×M4 or 2×M5, reckoning on the gear size.)Application: Mechanical transmission / motor / car / health kit / instrumentation / CNC machine instruments / toys / medical package / and so on.