12.000 Millimeter (mm) Nominal Shaft Diameter (d) Metric Bore Diameter ER Cartridge Inserts Ball Bearing

ER style bearings are insert bearings with an extended inner ring. They are specifically designed for mounting on shafts without using adapters, lock-nuts, or shoulders. They are popular in many applications due to their versatility, and cost effectiveness. The bearing is typically locked in place using setscrews (or a locking eccentric collar). The inner ring usually extends on both sides of the bearing to provide extra shaft support.