S6204ZZ Ball Bearing Premium ABEC-5 Quality with Si3N4 Ceramic Balls (Silicon Nitride) 20mm x 47mm x 14mm S6204ZZ Bearing is Double Metal Shields, radial and deep groove ball bearing,S6204ZZ bearing is made of Stainless Steel with Ceramic Balls (Si3N4) and Nylon Cage,S6204ZZ bearing is closed with 2 Metal Shields, one Shield from each side to protect the bearing from dust or any possible contamination,S6204ZZ bearing is sealed and self lubricated,the quality is set to EMQ (Premium ABEC-5 quality) to ensure high speed,S6204ZZ bearings is lubricated with grease.