Hubbell - CS8365CLocking Devices, Twist Lock, Industrial, Male Plug, 50A, 3 Phase Delta 250V AC, 3 Pole 4 Wire Grounding, Non NEMA, Screw Terminal, Black and White Super tough nylon housing offers better impact qualities Stainless steel shroud protects contacts and prevents mismating Heavy duty two piece external cord clamp provides maximum strain relief Box terminal with hex socket threaded slug, permits high clamping pressure on conductors without damaging strands