800 Skateboard/Inline Skate Black Bearings work with Roller Hockey Rollerblades Too Sealed & Nylon Cage 800 Skate bearings Work in RollerBlades and Scooters, bearings are Deep Groove Radial Ball Bearings, bearings have nylon cage that would make them faster, bearings have 2 Sealed, Bearings are made of Chrome Steel, each bearing has 2 Sealed to protect the bearing from dust or any possible contamination, also bearings are pre-lubricated with oil.