The Duo S from Petzl with the integrated rechargeable battery is the most powerful. While it does not allow the use of conventional batteries, it can be recharged directly, easily, economically and environmentally. The headlamp can also offer 5 lighting modes, the FACE2FACE function and balance by placing the battery on the back of the head. Included in the package are 110/240 V mains charger and two adapters (plates) for mounting on VERTEX and ALVEO helmets.