The LED Upgrade Kit converts most C & D (2-6 cell PR style flange) incandescent flashlights into long-lasting 55-lumen LED flashlights with a 100,000 hour life. For those who want to amp up the brightness, the High Power LED Upgrade Kit converts most C & D (2-6 cell PR style flange) incandescent flashlights into bright 74-lumen LED flashlights with a 50,000 hour life. It's as 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 environmentally-friendly pocketbook-friendly.