Abuse-resistant thermoplastic construction. Back wire terminal clamps for easy secure wiring. External cable clamp provides firm strain relief. Individual wiring compartments with tapered channel for easy insertion of wires. Clear cover over wiring compartments allow easy inspection of wiring terminations. Triple combination head screws standard - slot/Phillips/Robertson for use in the US and Canada. Clearly marked rating, standard compliances on face. 20 A - 125/250 V. NEMA L14-30.