S608-2RS Sealed Ball Bearing with Silicon Nitride Ceramic (Si3N4) Balls S608-2RS Ball Bearing is regular section, double sealed, radial and deep groove ball bearings,S608-2RS bearing is made of chrome Steel with silicon nitride ceramic balls (SI3N4) and Nylon cage,S608-2RS bearing is closed with rubber seals to protect the bearing from dust or any possible contamination,S608-2RS bearing is sealed and self lubricated,the quality is set to EMQ (electric motor quality),S608-2RS bearing is lubricated with grease.