SR12-2RS Stainless Steel Sealed Silicon Nitride Ball Bearing ABEC-5 Quality with Si3N4 Ceramic Balls 3/4" x 1 5/8" x 7/16" Inch SR12-2RS Stainless Steel Sealed Silicon Nitride Ball Bearing, Bearing is deep groove ball bearing, SR12-2RS bearing is made of Stainless Steel with Ceramic Balls (Si3N4) and Stainless steel cage, bearing is closed with rubber seals to protect the bearing from dust or any possible contamination, SR12-2RS bearing is sealed and self lubricated, the quality is set to EMQ (ABEC-5 quality) to ensure high speed, SR12-2RS bearing is lubricated with grease.