6304ZZ Shielded Ball Bearing 20mm x 52mm x 15mm 6304ZZ Shielded Ball Bearing, material is Chrome steel, 6304ZZ is Electric motor quality, each 6314ZZ bearings is closed with 2 Metal Shields, one Shield from each side, to protect the bearing from dust or any possible contamination, also 6314ZZ bearing is pre-lubricated with grease, Bearings 6314ZZ has industrial packaging.