S6805-2RS Sealed ABEC-5 Ball Bearing With Si3N4 Ceramic Balls 25mm x 37mm x 7mm S6805-2RS Sealed ABEC-5 Ball Bearing With Si3N4 Ceramic Balls, Bearings is made of Stainless Steel with Ceramic Balls (Si3N4) and Nylon cage, S6805-2RS bearing is closed with rubber seals to protect the bearing from dust or any possible contamination, S6805-2RS bearings is sealed and self lubricated, The quality is set to EMQ (ABEC-5 quality) to ensure high speeds, S6805-2RS bearings is lubricated with grease.