Thermostat Manifold Studs with 5/16 UNF Brass Nuts. Material : Steel. Thread: 5/16 x 1 13/16 UNC/UNF. Zinc quoted for rust prevention. Please check the lengths of these studs before you buy them. Short thread length 12mm (UNC Thread), Plain section length 14mm, Long thread length 19mm (UNF Thread), Overall Length : 45 mm ( 1 13/16" )