U-Line® Contender® plugs and receptacles offer all the advantages of U-Line technology without the need to replace competitors back boxes that have already been installed. Simply change out the receptacle and your company can benefit from the safety, flexibility and value of U-Line. Appleton provides its own compatible back boxes, so you can continue to expand your facility using a single vendor. U-Line Contender plugs and receptacles allow the use of electrical equipment in hazardous locations. In non-hazardous locations, the U-Line ECP plug fits into standard NEMA 5-20R and 6-20R receptacles. In hazardous locations, the same U-Line plug is the key to energizing the explosionproof U-Line receptacle. A twist of the plug makes electrical contact and locks the plug in place with an audible click. The neoprene gasket in the throat of the receptacle seals against the plug or the spring-loaded cover to seal out water, dust and corrosive compounds. Although U-Line plugs can be used with ordinary receptacles, U-Line receptacles are designed so that they cant be energized by an ordinary plug-ensuring that only safe connections can be made in a hazardous location.