Features: They are rubber sealed to avoid contaminants entering and save lubricant-. Made of high-quality metal for low noise and long service life. They have good wear-resistance and high stability. The bearing can create small friction and high-limit speed due to its smooth surface- and compact structure. Suitable for small hobby 5mm shaft/rod projects.Widely used for skateboard wheels, inline wheels, caster wheels, scooter wheels and industrial demands. The package includes total 10 pieces bearings which you may use for many different projects. They are also good replacements for your old one. Specifications: Material: metal Outer diameter: approx 16mm Inner diameter: approx 5mm Width: approx 5mm Note: Please allow 1-3cm error due to manual measurement. please make sure you do not mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Package includes: 10x Ball Bearings