S6806-2RS Sealed Ball Bearing Premium ABEC-5 Quality with Si3N4 Ceramic Balls (Silicon Nitride) 30mm x 42mm x 7mm S6806-2RS Sealed, radial and deep groove ball bearing,bearing is made of Stainless Steel with Ceramic Balls (Si3N4) and Nylon cage,S6806-2RS bearing is closed with rubber seals to protect the bearing from dust or any possible contamination,S6806-2RS bearing is sealed and self lubricated,the quality is set to EMQ (Premium ABEC-5 quality) to ensure high speed,S6806-2RS bearing is lubricated with grease.