Cord connector offers the strength of steel and the corrosion resistance of zinc plating. These heavy-duty connectors hold up to most manufacturing chemicals including acid solutions, solvents and other corrosive materials. Made of malleable iron. Cadmium plating. 3 inch NPT hub. -34 to 107°C effective operating temperature. 1.72 to 1.77 inch recommended knockout hole size. Suitable for use in hazardous locations per class I division 2, class II division 1 and 2, class III division 1 and 2 NEC reference 501-4 (b), 502-4 (a), 502-4 (b), 503-3 (a) and 503-3 (b).