Description: Miniature ball bearings are available ball bearings of quite small size. These miniature ball bearings have a 5mm inner diameter, a 8mm outer diameter, and a 2.5mm thickness. Ball bearings of this size are ideal for precision work and applications that require a lot of functional mechanical parts in a small space, such as 3D printer, quadcopter or model. Features: These miniature bearings are made of high quality bearing steel for low noise and long service life. They are double shielded to avoid contaminants entering and save lubricant. Bearings have a 5mm inner diameter, a 8mm outer diameter, and a 2.5mm thickness. These are great for small hobby 5mm shaft/rod projects such as 3D printer, quadcopter or ship model. There comes total 10 pieces miniature bearings which you may use for many different projects. Specifications: Material: Bearing steel Inner Diameter: 5mm / 0.19" Outer Diameter: 8mm / 0.31" Thickness: 2.5mm / 0.09" Quantity: 10pcs Package Includes: 10 x Bearings