Anycubic Aluminum 3mm Bore 20 Teeth Idler Timing Belt Pulley with Dual Ball Bearing for 3D Printers GT2 Belt Material: Aluminium Used in 3D Printers, CNC machines and other linear motion applications with 6mm wide timing belt Total width: 18mm,Bore diameter: 3mm,Groove width: 6.5mm Dual Ball Bearings are included Pack of 5PCS