The Retaining Ring is found on the underside of Ultrafeed^®, Leatherwork^®, Yachtsman and Stitch Master^® Sewing Machines. This is the component that holds the Shuttle Gib Hook in position. At the top of the ring there is a thin curved metal plate called the Retaining Ring Cap Spring (sold separately). This Cap Spring is secured with two screws (also sold separately). The Retaining Ring nestles inside the Shuttle Race Guide Shaft.