S61802-2RS Sealed Ball Bearing Premium ABEC-5 Quality with Si3N4 Ceramic Balls (Silicon Nitride) 15mm x 24mm x 5mm S61802-2RS Bearing is double sealed, radial and deep groove ball bearing,bearing is closed with rubber seals to protect the bearing from dust or any possible contamination,S61802-2RS bearings is sealed and self lubricated,the quality is set to EMQ (Premium ABEC-5 quality) to ensure high speed,S61802-2RS bearing is made of Stainless Steel with Ceramic Balls (Si3N4) and Stainless steel cage, bearings is lubricated with grease.