6813DDU Bearing is double sealed, radial and deep groove ball bearing, bearing is made of Chrome Steel with chrome steel balls and steel cage, 6813DDU bearing is closed with rubber seals to protect the bearing from dust or any possible contamination, 6813DDU bearing is sealed and self lubricated, the quality is set to EMQ (electric motor quality) to ensure high speed, 6813DDU bearing is lubricated with greased.