To raise the pressure of the cooling system raises the boiling point of the coolant. Spoon Radiator Caps raise the pressure to increase the efficiency of the cooling system. For the Complete Spoon Cooling System, we recomend using the Radiator Cap in combination withthe Spoon Thermo Switch, Spoon Thermostat and Spoon SEP Radiator Hoses. Please check with us for the correct type of Cap for use on your Vehicle - Type-F Caps suit older Honda Radiators such as EF9/EF8/DA9 etc. Also suitable for use on most aftermarket radiators such as Spoon, Koyo, Mishimoto etc.