RMS5ZZ Shielded Ball Bearing 5/8" x 1 13/16" x 5/8" inch RMS5ZZ Shielded Ball Bearing, RMS5ZZ bearing is made of Chrome Steel with chrome steel balls and steel cage, bearing is closed with Metal Shields to protect the bearing from dust or any possible contamination, RMS5ZZ bearing is Shielded and self lubricated,the quality is set to EMQ (electric motor quality) to ensure high speed, RMS5ZZ bearing is lubricated with grease.