Ground joint fittings are for heavy-duty applications such as steam, air supply for construction, roadbuilding and drilling applications. The coarse threads make G29 couplings easy to couple in the field and the heavy wing nuts can be tightened using a hammer or mallet. Collars on the hose stems are designed for use with G29C interlocking clamps. Typical hose assemblies will have G29S stems and G29N wing nuts on both ends fastened with G29C clamps. Hose lengths can then be joined using G29DS double spuds. Male and female spuds are used to adapt to pipe thread ends on valves, pipe fittings or manifolds. Ground joint fittings are made from plated ductile iron. Small size stems are plated carbon steel and small double spuds are brass.