Miniature bearings are sometimes referred to as instrument bearings and are used in applications as varied as gyros, anemometers, flow meters, miniature gearboxes, small motors and radio controlled models. Miniature ball bearings can be open or shielded, which helps prevent dirt from entering and lubricant from leaking out, and unflanged or flanged for easier plate mounting. Some miniature ball bearing options feature extended inner rings to help fit certain locking devices when a press fit is not possible.