S61901-2RS sealed Ball Bearing Premium ABEC-5 Quality with Si3N4 Ceramic Balls (Silicon Nitride) 12mm x 24mm x 6mm S61901-2RS sealed Ball Bearing is double sealed, radial and deep groove ball bearing,S61901-2RS 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,S61901-2RS bearing is sealed and self lubricated,inner diameter is 12mm, outer diameter is 24mm and width is 6mm,the quality is set to EMQ (Premium ABEC-5 quality) to ensure high speed,S61901-2RS bearing is lubricated with grease.