S6900-2RS Sealed Ball Bearing ZrO2 Ceramic Balls 6mm x 10mm x 2.5mm S6900-2RS Sealed ZrO2 Ceramic Ball Bearing, bearing is made of Stainless Steel with Ceramic Balls (ZrO2) and Stainless steel cage, S6900-2RS bearing is closed with rubber seals to protect the bearing from dust or any possible contamination, bearing is sealed and self lubricated, S6900-2RS bearing is lubricated with grease.