SR8-2RS ABEC-5 Bearing Si3N4 Ceramic 1/2" x 1-1/8" x 5/16" BearingSR8 2RS Sealed Ball Bearing ABEC 5 Quality with Si3N4 Ceramic Balls (Silicon Nitride) 1 2" x 1 1 8" x 5 16" Inch SR8 2RS Bearing is double sealed, radial and deep groove ball bearing,SR8 2RS bearing is made from 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,SR8 2RS bearing is sealed and self lubricated,SR8 2RS bearing is lubricated