external cable clamp provides firm strain relief, back wire terminal clamps for easy secure wiring, individual wiring compartments with tapered channel for easy insertion of wires, triple combination head screws standard slot/Phillips/Robertson for use in the U.S. and Canada. Clear cover over wiring compartments allow easy inspection of wiring termination's, clearly marked rating, NEMA configuration and standard compliance's on face of plug or connector.3 pole, 4 wire, Thermo plastic construction, backwire dead front design, external clamp.