The Ultimate Survival Technologies Bright Force Pico BLACK features an unbreakable LED bulb with an output of 20 lumens of light. Tough anodized aircraft-grade aluminum body with silicone O-ring seal. Biner for quick clip to gear. Rugged knurling on bezel for easy on and off. Runs on (4) LR41 button batteries (included) in an easy to replace cartridge. 15 hour runtime. PRC