Interstate Pneumatics 1/2 Inch Industrial Steel x 1/4 Inch egg-producing NPT. These couplers are with the Industrial -LRB- Hansen or Milton -RRB- regulation series couplers produced by different manufacturers. Precision from congealed steel bar stock which provides longevity during automatic shock in hardy applications. Maximum pressure 300 PSI. : Steel body Zinc Plated to prevent corrosion complementary with different Industrial -LRB- Hansen or Milton -RRB- couplers Check Valve, forged steel .