Killark UGP-15231QW - Factory sealed chamber in UGR receptacle contains switch’s arcing components. Spring loaded receptacle cover closes when plug is removed. Copper-free aluminum (less than 4/10 of 1%) alloy resists corrosion. Electrostatically applied and baked powder epoxy/polyester finish. ACCEPTOR® plugs conform to NEMAconfigurations, while it's “turn to engage” feature locks in plug and can be used to prevent accidental disengagement of critical equipment. Plugs for use with type S/SO/ST/STO heavy duty cord. The ACCEPTOR® UGP-QW / UGR-QW Plug and Receptacle system, with its unique patented design, is interchangeable with other NEMA bladed type explosion-proof and dust ignition proof devices. Plugs and receptacles may be used where bladed devices are needed in locations made hazardous by the presence of flammable gases or vapors, combustible dusts or easily ignitable fibers and flyings. Quick-Wire terminal construction allows for easier installation than traditional methods, allowing for labor savings and higher customer satisfaction. Plug can serve to provide power for portable equipment used in both hazardous and non-hazardous areas. Factory sealed construction specifies that no additional external seals are required (except in Group B applications). - Class I, Divisions 1 & 2, Groups C, D - Class I, Zones 1 & 2, Groups IIB, IIA - Class II, Divisions 1 & 2, Groups F, G - Class III, Divisions 1 & 2