Zero Sport Radiator Cap 1.3KThe Zero Sports Radiator Cap controls the water pressure in the cooling system by increasing the boiling point of the coolant. By increasing the boiling point, you decrease the amount of air bubbles that form in the coolant. Air is less effective at removing heat from the engine than coolant, so by reducing the air in your system, your coolant can more efficiently cool your engine. Controls the water pressure in the cooling system by increasing the