SR14-2RS Sealed Ball Bearing Premium ABEC-5 Quality with Si3N4 Ceramic Balls (Silicon Nitride) 7/8" x 1 7/8" x 3/8" Inch SR14-2RS Bearing is double sealed, radial and deep groove ball bearing,SR14-2RS 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,SR14-2RS bearing is sealed and self lubricated,the quality is set to EMQ (Premium ABEC-5 quality) to ensure high speed,SR14-2RS bearing is lubricated with grease.