Leviton 27W81 20-Amp, 120/208-Volt 3PY, NEMA L21-20R, 4P, 5W, Locking Connector, Industrial Grade, Grounding, Wetguard, Yellow EPTR rubber part provides outstanding resistance to wet and damp environments, extreme temperature variations, acids, alkalis, grease, oils and solvents IEC IP66 and IP 67 Rated, in accordance with IEC 529 as evaluated by UL and CSA Interlocking "tongue and groove" construction seals out water, moisture, dirt when plugs are mated with connectors Multi-point sealing system utilizes nut, strain relief washer and rubber bushing to form a watertight cord grip seal Non-magnetic stainless steel fast-threading assembly screws won't interfere with sensitive equipment