HKS Type 1 Radiator Cap, Fits many Toyota, Nissan, Infiniti and other import vehicles. Also fits the Koyo radiators we sell. Rated at 1.3 Bar or 18.5 psi. By using HKS high pressure cap, you can increase the boiling point of your coolant, which equates to better thermal transfer and stable water temp. Silicone radiator hoses also recommended.