This Grainger Approved cap fitting features thicker walls that can withstand higher pressures than class 150 fittings. - Model is suitable for air, water, oil, natural gas, and steam. Pipe Fitting Material / Galvanized Malleable Iron Fitting Schedule/Class / Class 300 Pipe Size - Pipe Fitting / 1/2 in Fitting Connection Type / FNPT Standards / ASTM A-197, ASTM A47, ASME B16.3 and B16.4, UL Listed, FM Approved Max. Pressure / 2000 psi @ 150 Degrees F WOG Saturated Steam Pressure / 300 psi