Two Aluminum GT2 Pulleys + 2 Meter of GT2 Belt + Hex wrench Set.Type: GT2Pitch: 2mmPulley teeth: 20Pulley bore: 5mm (for 5mm shaft)Pulley material: AluminumBelt wide: 6mmBelt material: quality rubber with reinforced fiberglassPlease see the drawing for dimension steps per mm， for your 3D printer firmware parameters.For 3D Printing applications， GT2 2mm belt system works better than T2.5， T5， it gives better smoothness and accuracy of positioning， resulting in better printing quality. GT2 timing belt system especially suited for linear movement and positioning applications.Package Included:Two Aluminum GT2 Pulleys + 2 Meter of GT2 Belt + Hex wrench