Features: These miniature bearing are made of 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 Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.