Features: These liner-motion bearings are made of high-quality bearing steel for low noise and long service life. They are double-sealed to avoid fomites entering and save lubricant. Bearings have a 12mm inner diameter, a 21mm outer diameter, and a 30mm height. These are great for small hobby 12mm shaft/rod projects such as 3D printers and engraving machines. There are total 10 pieces bearings, which you may use for many different projects. Specifications: Type: LM12UU Material: Bearing steel Inner Diameter: 12mm / 0.47" Outer Diameter: 21mm / 0.83" Height: 30mm / 1.18" Quantity: 10pcs Package Includes: 10 x Bearings Product Description: Ideal for glider rocker setups, our bearings offer smooth and frictionless movement, providing an effortless gliding experience along the rods. The linear motion bearing bushing design ensures precise linear motion without any unwanted play or wobbling, maintaining accuracy in your CNC machining or 3D printing projects. Compatible with various applications, including 3D printers and CNC machines, these bearings are versatile components suitable for different projects and setups. Whether you're a hobbyist, DIY enthusiast, or professional, our linear ball bearings are essential for achieving smooth and Consistent linear motion in your projects. Upgrade your equipment and enhance your workdrown out with our Consistent linear ball bearings today!