The Princeton Tec Impact XL uses a bright 1-watt LED to give you 50+ hours of true-spectrum white light with the included four AA alkaline batteries. LED technology is revolutionizing the lighting industry - the LED bulb life is 10000+ and they're misers on battery current usage. Rubber molded over the tough battery case gives you a secure grip on the light; it's waterproof to 100 meters and rugged. State-of-the-Art right in your hand. A new kind of flashlight that lasts for hours and hours.