Feature:1. It is generally used on 3D printers, and these bearings have proven to be long lasting and provide precise low friction linear movement2. Used for the design of linear motion products, and it is very convenient to use GT2 pulley and GT2 belt together3. The motor shaft coupler provides an extremely tight grip, and 20 teeth contact with the belt, which can minimize the belt slippage4. The aluminum alloy pulley has high quality shiny appearance and robust construction5. The kit is relatively complete, including different types of couplings, belts, pulleys and wrenches, which can save you the time to find additional partsSpecification:Item Type: LM8UU Linear Bearing KitMaterial: Stainless Steel + Aluminum AlloySpecification:12 x LM8UU4 x 608ZZ1 x 624ZZ2 x 5 * 8 Coupling1 x GT2 Belt2 x 20-Tooth Aluminum Alloy Synchronous Pulley1 x Hex WrenchFor i3 3D Printer Package List:12 x LM8UU4 x 608ZZ1 x 624ZZ2 x 5 * 8 Coupling1 x GT2 Belt2 x Pulley1 x Hex Wrench