Petzl DUO S Headlamp - The Petzl DUO S Headlamp runs on a rechargeable battery. Waterproof and durable, it is ideal for demanding sports such as caving, orienteering and cycling. Featuring the FACE2FACE anti-glare function, a Petzl patent, the DUO S headlamp allows users to face each other without blinding one another.