1、These bearings are made of high quality steel for low noise and long service life. 2、They are double shielded to avoid contaminants entering and save lubricant. 3、There are several different types and sizes of bearing that you can choose as needed. 4、These are great for small hobby projects, suitable for both professionals and enthusiasts. 5、There comes total 10 pieces bearings which you may use for many different projects. Features: These bearings are made of high quality steel for low noise and long service life. They are double shielded to avoid contaminants entering and save lubricant. There are several different types and sizes of bearing that you can choose as needed. These are great for small hobby projects, suitable for both professionals and enthusiasts. There comes total 10 pieces bearings which you may use for many different projects. Specification: Model(Optional) Inner Diameter Outer Diameter Thickness 604-ZZ 4mm / 0.2in 12mm / 0.5in 4mm / 0.2in 605-ZZ 5mm / 0.2in 14mm / 0.6in 5mm / 0.2in 606-ZZ 6mm / 0.2in 17mm / 0.7in 6mm / 0.2in Cage material: Steel plate Type: Deep-groove high-speed Usage: Universal Rolling Element: Single row steel balls Bearing Material: Bearing steel Angle: 15 degree Sealing: Double shielded Quantity: 10pcs Package list: 10 * Bearings