S61905-2RS Stainless Sealed Bearing Premium ABEC-5 Quality with Si3N4 Ceramic Balls (Silicon Nitride) S61905-2RS Bearing, categorized as thick section, double sealed, radial, deep groove ball bearing,bearing is made of Stainless Steel with Ceramic Balls (Si3N4) and Nylon cage,bearing is closed with rubber seals to protect the bearing from dust or any possible contamination,bearing is sealed and self lubricated,the quality is set to EMQ (Premium ABEC-5 quality) to ensure high speed,S61905-2RS bearing is lubricated with grease.