Usage Tips:Precision grade ABEC-1, maximum speed 34000, with grease. Pre-grease, low friction, no maintenance Single row radial ball bearings for applications supporting radial and axial loads Easy to disassemble and reinstall. Perfect products for medium loads: skateboards, inline skates, scooters, inline blade electric motors, bicycles, motorcycles, electric hand tools, etc. In many other rolling applications, refitting a worn skateboard to an inline blade electric motor of a skateboard scooter, wheels of bicycles and motorcycles, automobiles, electric hand tools, etc. For ball bearings, the radial internal clearance is C3, so that the radial slack between the inner ring and the outer ring is CN (normal) to compensate for thermal expansion. Heat treatment is performed to increase hardness to improve wear resistance. It has deep ball grooves in both seat rings and can withstand high radial and axial loads; its straight holes can be fitted with traditional cylindrical shafts; the nylon cage prevents the balls from contacting each other during use, Which reduces friction, vibration and noise. Removable single lip contact seals on both sides prevent contaminants from entering and maintain lubrication during manufacturing. The ball bearing is suitable for skateboard, inline skating and other roller skating applications. Note: Please check the size / dimensions or accuracy class (if suitable for your equipment). colour: black + silver Material: carbon steel Size: 8x22x7mm Package Contents: 100 x Ball bearings Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.