ABEC 9 determines the precision and tolerances of ball bearings. The higher the ABEC level, the better the quality, quieter operation, and speed, and our level is high, which can give you smooth and quiet bearings. Premium quality: These ball bearings are made of high-quality carbon steel with a long lifespan, smooth surfaces, high efficiency, and low noise. Each ball bearing has two blue low-friction rubber seals; the bearings are very well protected by the blue rubber seals. Ball bearings are easy to maintain, thereby significantly increasing their lifespan. Ride calmly and smoothly: These skateboard bearings are essential for the skateboard to move with as little friction as possible to reach the highest possible speeds. They prevent damage to the metal in the outer wheel and make it smoother. It is suitable not only for skateboards, longboards, and roller skates, but also for all wheel sizes, and also for high-speed travel and other high-performance applications, from workshops to agricultural machinery, roller guides, conveyor belts, robotics, dentistry, elevators, rolling mills, rudder shafts, aggregate crushers, and much more. Contents: 10 black bearings, 10 blue ball bearings, 10 red bearings. Three different colors that can make your skateboard cooler.