Skateboard bearings are the small round devices that allow your wheels to roll. They are all one size but differ in quality. The better the quality, the better your ride will be. Diamond Supply Co have created some of the fastest and smoothest skate bearings in the business. They come in a set of 8 and in a pretty swanky "diamond" case. They don't disappoint either. They have removable shields and are pre lubricated so you can roll straight out of the packet. Why would you have anything else when you can have "diamonds"!