Our Automotive Interchange Quick Connects have plated steel, brass, or stainless couplers with hardened steel balls, stainless springs, and Buna-N seals (other seals are available on special request). The nipples are heat treated to reduce wear on critical mating surfaces and the maximum working pressure is 300 psi in all sizes (3/4" body are 220 psi). Brass are non-sparking and provide greater corrosion resistance over steel, but being a soft metal the brass will wear more quickly than the steel.