Features： 1、DURABLE MATERIAL: Made of aluminum alloy, surface oxidation treatment, durable, fine workmanship, high transmission accuracy, closed timing belt is made of strong fiber reinforced rubber, durable and elastic, has long service life, bringing you an unparalleled experience 2、ACCURATE AND FIRM: Providing accurate transmission. No slippage during work, constant transmission ratio 3、SUITABLE FOR DIY: Bring smooth transmission, accurate pitch, high transmission efficiency, good energy saving effect, many DIY enthusiasts are full of praise for it, and will also be your best choice 4、SIMPLE STRUCTURE: Easy installation and disassembly, with a wrench, used together to make your 3D printer work easier and more convenient 5、WIDE APPLICATION: As a stepper motor pulley kit, widely used in 3d printers, milling machines, gear grinding machines, drilling machines, CNC lathes, gear hobbing machines or other mechanical transmission occasion Specification： Item Type: Synchronous Wheel Material: Aluminum alloy, rubber Timing Belt: Length: Approx. 200mm / 7.87in, Width: Approx. 6mm / 0.24in Teeth: 20T and 60T Screw: M4 Package List： 4 x Synchronous Wheel 2 x Belt 1 x Hex Wrench