S627-2RS Sealed Ball Bearing ABEC-7 Quality with Si3N4 Ceramic Balls (Silicon Nitride) 7mm x 22mm x 7mm S627-2RS Sealed Ball Bearing is double sealed, radial and deep groove ball bearing,bearing is made of Stainless Steel with Ceramic Balls (Si3N4) and Stainless steel cage,S627-2RS bearing is closed with rubber seals to protect the bearing from dust or any possible contamination,bearing is sealed and self lubricated,the quality is set to EMQ (ABEC-7 quality) to ensure high speeds,S627-2RS bearing is lubricated with grease.