With 1100 lumens, the Duo S has extremely high luminosity. It is waterproof up to -1 meter for approx. 30 minutes, battery operated and extremely robust. This makes it ideal for demanding outdoor sports (speleology, orienteering, biking, etc.) The Duo S is equipped with Petzl's patented Face2Face anti-glare function so as not to dazzle its counterpart, which makes group movement more pleasant. Five light modes are available to the user as required. These range from a wide cone with low luminosity and long luminosity to boost mode for short-term access to the maximum luminosity of 1100 lumens. The lamp has a large, ergonomic switch that is easy to operate even when wearing gloves. An electronic lock protects against unintentional switching on during transport and when the light is not in use. The battery housing carried on the back of the head creates a balanced weight distribution. If the battery is almost empty after a long tour, the Duo S automatically switches to reserve mode.
With Constant Lighting headlamps, the luminous intensity does not change during the specified light duration. This luminous intensity is below the maximum value when the lamp is switched on. At the end of the light duration, the lamp automatically switches to reserve mode with reduced luminosity.