Cast device box made of both malleable iron and aluminium boxes have ridge top construction for positive cover/gasket/box fit. Corrosion-resistant, ideal for indoor and outdoor installations. Weatherproof, rain tight and dust-tight when used with cast casketed covers. Accurately tapped, tapered threads for tight, rigid joints, ground continuity. Covers have captive stainless steel screws to speed installation, prevent freezing of screws. Aluminium boxes and covers are epoxy powder coated.