The Nite Ize High Power LED Upgrade Kit converts most C & D (2-6 cell PR style flange) incandescent flashlights into super-bright, long lasting LED flashlights. It's as easy as replacing the bulb - and instantly, your flashlight will emit a pure white LED light. Self-adjusting for all capacity levels, this efficient LED technology also conserves battery use, making it not only a useful, versatile improvement, but an environmentally-friendly one as well.