Specification: Rail Guide Total Size: 8mm x 150mm; SK8 Rail Support Size: 33 x 42 x 15 mm/1.3 x 1.7 x 0.6 inch (LxWxH); SCS8UU Ball Bearings Size: 30 x 35 x 22 mm/1.2 x 1.4 x 0.9 inch (LxWxH) Material: The linear motion rod shaft guide set is manufactured from aluminum alloy and carbon steel materials to strength, durability, and smooth operation, and the precise design ensures reliable linear motion. Linear Motion System: The linear motion rail shaft slide guide offers stable support and precise linear movement with the help of the bearings and rail support, bearings smooth gliding and rail supports provide sturdy vertical support, ensuring safe operation and maintaining accurate positioning. Easy to Use: Install the linear motion rail shaft onto the appropriate structure or framework using the provided mounting holes, and then attach the SCS8UU ball bearings and SK8 rail support to the moving parts of your CNC machine or 3D printer. that the slider blocks slide smoothly along the rail shaft, and adjust the position of the anti-collision block stopper as needed. Wide Application: This linear motion rail shaft slide guide system is suitable for CNC machines and 3D printers, providing precise and reliable linear motion control, so is great for various applications such as engraving, milling, cutting, and printing to smooth and accurate movement in these machines. Please regularly inspect and maintain the linear motion system to optimal performance. Colour:As Shown Material:Metal Package Contents: 2 x Rail Guide 4 x SCS8UU Ball Bearings 4 x SK8 Rail Support Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.