S6808-2RS Sealed Ball Bearing Premium ABEC-5 Quality with Si3N4 Ceramic Balls (Silicon Nitride) 40mm x 52mm x 7mm S6808-2RS sealed, radial, deep groove ball bearing,S6808-2RS 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,S6808-2RS bearing is sealed and self lubricated,the S6808-2RS inner diameter is 40mm, the S6808-2RS outer diameter is 52mm and the S6808-2RS width is 7mm,the quality is set to EMQ (Premium ABEC-5 quality) to ensure high speeds,S6808-2RS bearings are lubricated with grease.