Annular thin plate components used for gap adjustment and positioning between shaft and housing in bearing parts of mechanical equipment and facilities. These precision metal rings are inserted between bearing inner/outer rings and shafts or housings to achieve proper fit and axial positioning. With precise dimensional tolerances ranging from 0.1mm to several millimeters thickness, they are widely used in machining equipment, industrial robots, and machine tool spindles. Also called shim rings, adjustment rings, or spacer rings, these components are essential for preload adjustment and axial play elimination during bearing replacement. Unlike washers or gaskets, they are positioned as mechanical element parts specialized primarily for dimensional adjustment functions.