The bearings are high carbon steel, 't worry about durability and resistance to deformity under heavy loads during jump, slide and . As you is easy to get and soil into the bearing which will slow down the bearing while we are sliding outdoor. Bust Bearing with on both sides will keep out and save our bearings. Suitable for skateboards wheels, scooters, Longboards, Roller Skates or other skating applications . With a smooth surfaces and clear engraving, these bearings not only provide a professional look but also low noise and high rotational speed. Package includes: 10Pcs Ball Bearings