Industrial Grade Locking Plug, NEMA L14-30P 30 Amp, 125/250 Volt, 60Hz, 3-Pole, 4-Wire Grounding Made of Polycarbonate Thermoplastic (PCT) material to provide the durability and resilience to withstand hard impacts and heavy force Easy to use for do-it-yourself installation; twists to lock with connector 66492-BK, NEMA L14-30C 2 pack; one-year warranty; UL Listed