Feature 1[ACCURATE SIZE] The set contains 10 pcs linear ball bearings for use, with inner diameter of 12mm, outer diameter of 21mm and height of 30mm. 2[HIGH STRENGTH] These linear motion ball bearings are made from alloy steel, with high tensile strength and hardness. 3[LASTING LIFE] Alloy steel linear motion bushings are resistant to damp, corrosion, acid and rust, ensuring lasting use. 4[LOW FRICTION] The linear bearings have smoothly surface, low noise, low friction coefficient and high track accuracy. 5[WIDE USAGE] Cylinder linear bearings are suitable for industrial automation equipment, such as 3D printer, engraving machine, XYZ module, etc.SpecificationItem Type: Linear Ball BearingMaterial: Alloy SteelModel: LM12UUInner Diameter: Approx. 12mm/0.5inOuter Diameter: Approx. 21mm/0.8inHeight: Approx. 30mm/1.2inUse: Widely used in various industrial fields such as machine tools, construction machinery, robots, speed reducers, steel, metallurgy, textiles, mining, printing, aerospace, and so on .wang-edit-text{ font-family:'Arial' !important; } .wang-edit-text table { border-top: 1px solid #000; border-left: 1px solid #000; } .wang-edit-text table td, .wang-edit-text table th { border-bottom: 1px solid #000; border-right: 1px solid #000; padding: 3px 5px; } .wang-edit-text table th { text-align: center; }Package List10 x Linear Ball Bearing