Features Details SBR Linear Guide Rail Set:SBR12-1000 mm Linear motion guide rail includes 2 x 39.4 in/1000 mm length SBR12 guide rails and 4 x SBR12UU slide blocks. Dynamic Load Per Block: 372 N, Static Load Per Block: 549 N. Durable Long-lasting: The linear rail is made of carbon steel and aluminum with a chrome-plated surface for rust resistance and high durability. Built-in 4 aluminum slide blocks and ball bearings for smooth and unobstructed sliding. Low Noise Sliding: Aluminum SBR slide blocks and carbon steel linear shaft are perfectly paired. The built-in ball bearing provides low friction movement and is smooth and not tilted, allowing you to control more labor-saving. High Precision: Precise circular shaft dimensions and straightness, ensuring high accuracy, repeatability, and stability in its motion. The sturdy aluminum base and slide block have accurate mounting holes, making it easy for users to perform reliable installation and connection. Wide Application: The SBR linear rail set is versatile and suitable for all kinds of high-load automation equipment and DIY project, such as router/mill/lathe sleds, 3D printers, laser engravers, CNC machines, trainer rocker plates, etc.