... :ductile iron,steel 2)Process:CNC machining 3)Standard: according to customer Coupling nut1) Material: stainless steel, alloy steel, grey ... , construction, electric appliance, military equipment, etc.3) Standard: according to the dimension tolerance of machining of customers’ requirement.4) Size:M6 ... , chrome-plated, hot-galvanized, sandblasting, painting, powder-coating. hex/round coupling nut