Top off your radiator with Billet Specialties New Black dome style radiator cap. Featuring a 6061-T6 billet aluminum top with knurled grip sides in 16 lb. caps. Please note: 16 lb. caps are for use on new replacement radiators like Walker, PRC, BeCool, Afco, etc. You will want to use the highest lb. radiator cap that you can as for each lb. of pressure in your radiator, it will increase the boiling point of your antifreeze by 2 degrees.