Teeth Type: 20 & 36 Teeth. Bore Diameter: 6.35mm. Belt Width: 6mm. Synchronous Wheel Material: High quality aluminum, anti-rust & anti-corrosion. Application: Widely used in 3D printer, CNC, milling machine, gear forming machine, drilling machine, CNC machine tool lathe, hobbing machine and other mechanical transmission occasions. Specification: Colour:Silver + Black Material:Metal + plastic Package Contents: 2 * Timing idler 20 teeth 2 * timing idler 36 teeth 2 * 200mm closed loop timing belt 1 * hexagon wrench Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.