UC204-20mm Black Oxide Plated Insert 20mm Bore BearingUC204 20mm Black oxide Plated Insert Ball Bearing 20mm Inner Diameter UC204 20mm Plated Insert Ball Bearing, bearing is wide inner ring with spherical outer ring, bearing is relubrication groove with oil hole on set screw side, bearing is anti rotation pin on side opposite grease groove, bearing is nylon patched class 3A set screws. UC204 20mm Bearing Plated Insert Ball Bearing Rings and Ball Material: SAE 51200 Retainer: Two Piece Riveted Steel Shaft