The spud part of the coupling serves as one half of the Boss Ground Joint connection and is usually fixed to the equipment. The stem part that is clamped to the hose is the other half. The two halves are connected or disconnected by rotating the wing nut on the spud. When connected they achieve both a mechanical and a pressure seal. Leakproof and easy to seal. Recommended for steam service up to 450°F. Works with existing Ground Joint fittings.