Features: These miniature bearing are made of high quality steel and ceramic for low noise and long service life. Bearing with ceramic balls is better resistant to corrosion and rarely require lubrication. Bearing has a 8mm inner diameter, a 22mm outer diameter and a 7mm thickness. These 608 bearing are specially designed for inline roller skate to improve speed. The lighter balls allow the bearing to spin faster, and uses less energy to maintain its speed. Specifications: Material: Steel(races), zirconia ceramic(balls) Inner Diameter: 8mm / 0.31" Outer Diameter: 22mm / 0.86" Thickness: 7mm / 0.27" Quantity: 16pcs Package Includes: 16 x Bearings 1,These miniature bearing are made of high quality steel and ceramic for low noise and long service life 2,Bearing with ceramic balls is better resistant to corrosion and rarely require lubrication 3,Bearing has a 8mm inner diameter, a 22mm outer diameter and a 7mm thickness 4,These 608 bearing are specially designed for inline roller skate to improve speed 5,The lighter balls allow the bearing to spin faster, and uses less energy to maintain its speed