Features: These solid polymer LM8UU bearings can eliminate vibration and unnecessary noise. If you add the lubricating oil, the smooth degree will be better. This sold polymer Linear bearing is a direct replacement for the metal LM8UU bearing. Commonly used in many 3D Printers, etc small making use(Large machines are not recommended). These solid polymer LM8UU bearings are great for RepRap, for Prusa, for Mendel, etc. Specifications: Model: LM8UU External diameter: 16mm/0.63inch Inner diameter: 0.8cm/0.31inch Length: 25mm/0.98inch Purpose: 3D printer Weight: 35g Oil lubrication method: drip lubrication(lubrication not included) Package Included: 8 x Solid Polymer LM8UU Bearing 1These solid polymer LM8UU bearings can eliminate vibration and unnecessary noise 2If you add the lubricating oil, the smooth degree will be better 3This sold polymer Linear bearing is a direct replacement for the metal LM8UU bearing 4Commonly used in many 3D Printers, etc small making use(Large machines are not recommended) 5These solid polymer LM8UU bearings are great for RepRap, for Prusa, for Mendel, etc