Petzl designed the Duo S Headlamp to brighten some of the darkest places in the world. It offers powerful reliable lighting for caving backpacking cycling mountaineering trail running rappelling in the dark or walking the dog at night although that may be overkill. The headlamp features Petzl's own Face2Face technology an anti-glare function that automatically dims the light when two or more beams cross so multiple users won't blind each other. In addition the headlamp offers five modes: a low-intensity flood beam to maximize battery life a mixed beam that is designed for proximity vision a focused beam for movement a powerful beam for anticipating the terrain when you're moving rapidly and a high-focus long-distance beam. A rechargeable battery makes the headlamp ideal for travel and longer adventures. Since it charges in four hours you can throw it in the charger overnight to always ensure you have full power when you need it. The control button is easy to operate even with gloves on and a lock mechanism prevents the headlamp from accidentally turning on in your pack. And with water-resistance down to 3. 28ft and high impact-resistance its built to handle whatever you may find on your travels.