Stanley Proto JFF160 Proto Spill-Free Funnel Threaded cap and adapter for newer GM -inch threaded style-inch radiator openings Eliminates trapped air pockets which can cause erratic cooling system and heater performance Controls amount of coolant entering system and enables unattended filling of the cooling system Eliminates squeaky belts caused by coolant overflow and protects the environment Includes four adapters which fit most domestic and foreign vehicles and light trucks