Made just like Henry made them. These special prop knobs hold the open car top irons onto the car. U.S.A.
The standard design was 1 1/2" in diameter, and painted black. 7/16-14 thread. A-37708-STD 1926-31 The deluxe has a polished stainless steel face with a steel back plate. 1-1/2" dia. 7/16-14 thread. A-37708-DEL 1930-31 The Cabriolet used a larger diameter. 1-7/8" knob with a polished stainless cover. 7/16-14 thread. A-37708-CAB 1928-31 The Sport Coupes used this knob that has a stainless face, and a special thread size in the back plate. 3/8-24 thread. A-37708-SP 1928-31.