SR2-2RS Sealed Ball Bearing Premium ABEC-5 Quality with Si3N4 Ceramic Balls 1/8" x 3/8" x 5/32" inch SR2-2RS Bearing is double sealed, radial, deep groove ball bearing,bearing is made of Stainless Steel with Ceramic Balls (Si3N4),bearings is sealed and self lubricated, the quality is set to EMQ (Premium ABEC-5 quality),inner diameter is 1/8" inch, outer diameter is 3/8" inch and width is 5/32" inch.