The pulleys are produced by high- automatic lathe machining, with machining error within 0.005mm. Smooth motion, high printing , low noise, can greatly the printing speed. Perfect for 3D Printers: -10, -10S, Tevo Tarantula, router hybrid, 8020 3030 and so on. This pulley bearing adopt of Motor grade bearings, rust resistant, wear resistant, friction resistance and operate smoothly. Used for 3D Printers, NC Engravers, Hot Wire Machines, , Camera Sliders, Plasma , Robotics, Furniture, And other DIY machine It is measured by professional instruments and the advantages and characteristics of the pulley work. Smooth motion, low noise, high printing accuracy, and greatly improved printing speed. Colour:Transparent Material:Polycarbonate Package Contents: 20 x Polycarbonate Pulley Only the above package content, other products are not included. Note: Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.