Smooth, rounded integral bushings in hubs protect conductor insulation Accurately tapped, tapered threads for tight, rigid joints and excellent ground continuity Roomy interiors provide more wiring space Furnished with four tapped holes and two close-up plugs. Boss in rear of box allows for fifth entry, factory or field entries, 1/2 or 3/4 in Malleable iron boxes offer high tensile strength, ductility, corrosion resistance and impact and shock-resistance