Features： 1、Aluminum Alloy Pulley: The pulley is fine made of aluminum alloy material, and the surface is oxidized, which is anti aging, has high strength and long service life. 2、Rubber Timing Belt: The closed timing belt adopts fiber reinforced rubber, which is full of elastic, provides working performance. 3、High Performance: The pulley set transmits smoothly and non slip, with precise teeth pitch and constant transmission ratio, efficient and energy saving. 4、Easy Installation: The pulley kit is simple in structure, comes with a wrench, easy to install and disassemble, making your 3D printer work easier and more convenient. 5、Wide Purpose: This pulley kit can be widely used in 3D printer, milling machine, gear grinding machine, drilling machine, CNC lathe, gear hobbing machine or other mechanical transmission occasion. Specification： Item Type: Timing Pulley Set Material: Aluminum Alloy, Rubber Timing Belt: Length: Approx.280mm/11in Width: Approx.6mm/0.24in Number of Teeth: 20 and 60 teeth Screw: M4 Package List： 4 x Timing Pulley 2 x Belt 1 x Hex Wrench