1/4" NPT, M Style, Coupler & Plug Kit, Made Up Of A Brass Body, Brass Sleeve Coupler & Steel Plug, With 1/4" Basic Flow Size & Air Flow Of 40 Standard CUFT Per Minute, Coupler & Plug Combination Has A Maximum Pressure Of 300 PSI & A Buna-N Seal, Maximum Temperature Of 250 Degrees Fahrenheit.