This is an antique automotive threaded grease cap manufactured by the Hayes Wheel Company of Jackson, Michigan. The object is constructed of cast brass and features a hexagonal top designed for wrench application, which transitions into a rounded, threaded body. The face of the cap contains embossed lettering in a circular composition. The central brand name HAYES is rendered in a stylized font where the H and S are oversized, framing the smaller letters. The top of the face is marked U.S.A. and the bottom is marked JACKSON MICH. This type of hubcap was commonly used on early 20th-century American automobiles equipped with wooden-spoke artillery wheels. Diameter: Approximately 2.5 inches.