Features: <br>These liner-motion bearings are made of high quality bearing steel for low noise and long service life. <br>They are double sealed to avoid contaminants entering and save lubricant. <br>Bearings have a 12mm inner diameter, a 21mm outer diameter, and a 30mm height. <br>These are great for small hobby 12mm shaft/rod projects such as 3D printer, engraving machine. <br> <br>There comes total 10 pieces bearings which you may use for many different projects. <br> <br> <br>Specifications: <br>Type: LM12UU <br>Material: Bearing steel <br>Inner Diameter: 12mm / 0.47" <br>Outer Diameter: 21mm / 0.83" <br>Height: 30mm / 1.18" <br>Quantity: 10pcs <br> <br> <br>Package Includes: <br>10 x Bearings<br>1、These liner-motion bearings are made of high quality bearing steel for low noise and long service life <br>2、They are double sealed to avoid contaminants entering and save lubricant <br>3、Bearings have a 12mm inner diameter, a 21mm outer diameter, and a 30mm height <br>4、These are great for small hobby 12mm shaft/rod projects such as 3D printer, engraving machine <br>5、There comes total 10 pieces bearings which you may use for many different projects