The Nite Ize LED Upgrade Kit converts most C and D (2-6 cell PR style flange) incandescent flashlights into bright, long lasting (100,000 hour) LED flashlights. It is easy as replacing the bulb - instantly, your flashlight will emit a pure white (as opposed to the incandescent dull 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 and pocketbook-friendly one as well.