High-pressure radiator caps help to insure against overheating. Raising your coolant pressure will raise the coolant boiling point (1 psi adds approximately 2°F to the boiling point, depending on your coolant mixture).
These Stant racing radiator caps are available with two different pressure settings: 20 psi (holds between 18 and 22 psi) or 23 psi (holds between 21 and 25 psi). The "Lev-R-VenT" lever allows you to manually release any remaining pressure safely before removing the cap. Each fits standard full-size radiator necks. Sold individually.
Before installing a high-pressure cap, have your cooling system inspected and pressure checked to make sure that it can handle the increased pressure.