Brass construction; Safety coded pressure device; NPT Fitting, Universal, Tube Fitting, 175 PSI Safety Valve 1/4M, Safety Valve - 1/4" M NPT - 175 PSI pop-off., 170 PSI Safety Valve 1/4M, Safety Valve - 1/4" M NPT - 175 PSI pop-off, 170 PSI Safety Valve.