The restrictor goes in the lower radiator hose replacing the thermostat restrictor to keep the water in the radiator longer. Therefore, the water is cooler when it reaches the engine. Machined aluminum available for the aluminum racing radiators. Designed to help the flow of your cooling system. The divider protrudes into the intake to separate water flow from side to side. So there is less interference and back pressure. Will fit cast iron or aluminum intakes. This is the combo to save you some money.
