Appleton GR/GRF explosion-proof outlet boxes complies with a wide range of classified area requirements. Corrosion-resistant ideal indoors or outdoors. For pulling of wires. Connect conduit lengths and change direction of conduit runs. Provide access for maintenance. GR boxes offers ten hub arrangements.GRF boxes have integral mounting flange. Malleable iron bodies have high tensile strength, ductility and provides great resistance to corrosion, impact, and shock. Accurately tapped, tapered hub threads for tight, rigid joints and ground continuity. Furnished with covers. General purpose wiring. Function as sealing fittings when used with sealing covers.Internally threaded body with externally threaded cover.Covers have pry notches for bar or wrench. Accommodate sealing, dome, hub and union hub covers and canopies. Standard O-rings provide raintight fit Nema 3&4. Internal ground screw standard. Smooth, rounded integral bushing in each hub type box protects conductor insulation.