This SBR Linear Guide Rail Set is designed for smooth and efficient motion. It includes two 39.4 inch/1000 mm SBR20 guide rails and four SBR20UU slide blocks. The components are constructed from durable carbon steel and aluminum with a chrome-plated surface for rust resistance. The built-in ball bearings in the aluminum slide blocks ensure low friction and stable, labor-saving movement. With precise dimensions and straightness, this kit offers high accuracy, repeatability, and stability for automated machines and DIY projects like CNC routers, 3D printers, and laser engravers. The sturdy aluminum base and slide block feature accurate mounting holes for easy and reliable installation.