ER Series: The ER Series® are precision ground radial bearings designed for demanding applications. This series of bearings feature exclusive heavy duty seals and are pre-lubricated for a long life. These bearings are also supplied with re-lubrication holes in the outer ring to facilitate re-greasing. The ER bearings also have a steel trash guard and inner ring labyrinth groove to provide superior protection of sealing member which offers better protection in wet/moist environments. The ER series is offered with or without a Black Oxide Coating which provides added corrosion resistance.