8 Skateboard Ceramic Bearing Sealed ZrO2

8 Skateboard Bearings, 608 Steel ball bearings are high speed solid Ceramic Balls, every bearing has a Steel high speed ball retainer, inside them there are Zirconia fibers 7 Ceramic balls, with a non-contact rubber seal, inner and outer races are made of Steel, 7 balls are made of Ceramic Zirconia fibers, each bearing has 2 non-contact rubber seal to protect the bearing from dust or any possible contamination.