2 x 20 Teeth GT2 Aluminum Pulley 1 x 2-Meter length GT Fiberglass Reinforced Rubber Open Belt (5m pitch x 6mm wide).The Aluminum GT2 Timing Pulley 20 Tooth 5mm Bore For 6mm Belt is for precise motion control, GT2 belts, and pulleys offer excellent precision at a great price.  This pulley has 20 teeth and a 5mm inner bore. Two set screws can be used to attach it firmly to any 5mm diameter shaft. Full aluminum construction means these are very light and very dur