1633ZZ Sealed Ball Bearing 5/8" x 1 3/4" x 1/2" inch 1633ZZ Bearing is regular section, double Shielded, radial and deep groove ball bearing, bearing is made of Chrome Steel with chrome steel balls and steel cage,1633ZZ bearing is closed with Metal Shields to protect the bearing from dust or any possible contamination, bearing is Shielded and self lubricated,the quality is set to EMQ (electric motor quality) to ensure high speed,1633ZZ bearing is lubricated with grease.