8 Skateboard Bearings 608-2RS BRONZE Cage Black Color Set of 8 skateboard ball bearings, the set has 8 Oil Preserved deep groove sealed Black Ball Bearings with BRONZE cage. The Bronze material is one of the least friction and it is a cupper alloy, less friction means less heat and higher speeds.Bearings are sealed with 2 Rubber Seals, Bearings are made of Chrome Steel, each bearing has 2 Rubber Seals to protect the bearing from dust or any possible contamination, also bearings are OIL preserved.