The Minimus headlamp features a high-efficiency LED that provides a brilliant white light, adjustable in output from zero to 100 lumens via the knurled no-slip right-hand output control knob. The proprietary refractive optic produces a wide beam optimized for your natural field of view, and an included red filter gives you the option of low-signature light that also preserves dark-adapted vision. A valuable safety feature: a setting for a long-running SOS beacon. The Minimus runs on a single 123A battery contained within the tilt-control knob, and the battery access cap has a short leash to prevent dropping or loss. The fine-weave headband is strong but comfortable, and features a moisture-wicking Breathe-O-Prene forehead pad. Built from tough polymer and hard-anodized aerospace aluminum, the Minimus is lightweight, yet like its siblings the Minimus Vision, the Minimus Tactical, and the Minimus AA, it"s tough enough for the rigors of combat, caving, and mountaineering, and is submersible to 3 feet for up to thirty minutes.