The Nite Ize LED Upgrade Kit converts your C or D cell Maglite into a bright, long lasting (100,000 hour) LED light. It's as easy as replacing the bulb: simply pop the upgrade kit in and instantly, your flashlight will emit a pure white (as opposed to the incandescent yellow) light, in spot to flood focus. Self-adjusting for all capacity levels, this efficient LED technology also ensures a much longer battery life, making it not only a useful, versatile improvement, but an environmentally friendly & wallet friendly one too!