Zinc Anode Sacrificial for Cooling System 240Z 260Z 280Z 510 280ZXZinc anode for reducing corrosion in the cooling system. This brass fitting has 1 4" NPT threads with a zinc anode attached. Simply install the threaded fitting anywhere in the radiator or engine cooling system. Keeps engine coolant electrolysis corrosion from attacking engine components. *We have had success installing this fitting into the threaded port (often unused) on the thermostat housing (see pic). Although the threads are not idenctical (BSPT