1638-2RS Sealed Ball Bearing 3/4" x 2" x 9/16" inch 1638-2RS Sealed Ball Bearing is radial, deep groove ball bearing,1638-2RS bearing is made of Chrome Steel with chrome steel balls and steel cage,1638-2RS bearing is closed with rubber seals to protect the bearing from dust or any possible contamination,1638-2RS bearings are sealed and self lubricated, the quality is set to EMQ (electric motor quality) to ensure high speed,1638-2RS bearing is lubricated with grease.