Quantity: 8 packs of 608 ZZ ball bearing skateboard. (The inner diameter is 8mm, the outer diameter is 22mm, and the total width is 7mm). High-quality materials: Skateboard ball bearings are made of bearing steel, are durable, have good durability, high speed, good strength and durability, have good deformability under heavy loads, are quiet, and reduce friction. It is suitable for products requiring rotation, low friction torque, low vibration, and low noise. Protection: The sealing material is stainless steel, which can effectively prevent foreign matter from outside the bearing (dust) from entering the ball bearing and damaging the bearing. Our products are very smooth. The smear limit for grease is 34,000 rpm. The service life can be extended by adding appropriate lubricating oil. Widely used in: scooter bearing, roller boards, roller skates, skateboard bearings, ball bearing inline skate accessories, toy models, office equipment, micromotors, instruments, laser engraving, small clocks, soft drives, pressure rotors, dental drills, hard disk motors, stepper motors, magnetic drum for video recorder. Metal density: The sealing material is made of stainless steel, which can effectively prevent the outside of the roller bearing (dust), foreign matter and debris from entering the bearing and damaging the bearing No maintenance required: Low friction coefficient, suitable for high-speed operation and very durable Widely used in: Skateboards, scooters, roller skates, skateboards, toy models, office equipment, micro motors, instrumentation, laser engraving, small clocks, soft controls, pressure rotors, dental drills, hard disk motors, stepper motors, video recorder drums Warm reminder: After receiving the goods, the bearings are greased. This is to keep the bearings lubricated and reduce friction during transportation. Make future work more durable.