The pulleys are produced by high-precision automatic lathe machining, with machining error within 0.005mm.Advantages: Smooth motion, high printing precision, low noise, can greatly improve the printing speed.Perfect For 3D Printers: for -10, -10S, Tevo Tarantula, CNC router hybrid, 8020 3030 and so on.With Bearings: YesPlease Kindly Note: the pulley has of many kinds size,please confirm correctly before you bought.Outside Diameter: 0.94inch/23.89mmInner Diameter: 0.62inch/16mmBore: 0.19inch/5mmThickness: 0.4inch/10.23mmSize: 24*6*5mmColor: BlackMaterial: steel + rubberPackage Contents:12 * 625zz POM WheelOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.