[Sintron] 12pcs LM8UU Linear Ball Bearing Bush Bushing for 8mm Rod RepRap 3D Printer Prusa Mendel i3 Kossel Delta etc. (1) The universal Bearings Ball is great for you to replace the damaged Ball Bearings in your devices to improve them efficiency and save energy. (2) The bearing is made of carbon chromium bearing steel, through hardened and precision ground handling, providing safe and reliable for the bearing sleeve and the bearing housing assembly. (3) Ball in the cage loop to run a smooth ball guide surface to ensure even if high-speed operation, low noise. (4) Great for linear motion on 3D Printer, CNC, and other applications . (5) We not just sell them, we also provide professional after-sales service, so welcome to discuss with us, we will try to do technical support as much as we can.