The UFO-LED enclosure and cover are constructed of heavy 22 gauge steel with a white paint finish. The unit contains a solid state charger with automatic transfer circuit, LED charge indicator light, and a high temperature Nickel-Cadmium battery. The UFO-LED does not affect normal fixture operation and may be used with a switched or unswitched fixture. If a switched fixture is used an unswitched AC power supply must also be connected to the UFO-LED, and must be fed from the same branch circuit as the fixture?s AC ballast. For remote installation, the UFO-LED may be installed up to 250 feet from the fixture. UFO-LED provides full lumen output during emergency illumination for a minimum of 90 minutes. UL 924 Damp Location Listed