3D SlimFit Construction. By integrating the electronics into the fabric with a specially shaped housing, the entire lighting unit is packaged into an ultra-thin casing that fits as seamlessly as a contact lens. With a front profile of just 10 mm and a weight of only 78 g, the HeadLamp 425 sits flush on the forehead without wobbling or slipping. The headlamp moves as a single unit, and you quickly forget that it’s even there. Red rear light for added visibility. The new integrated light on the back ensures that you are seen by other hikers, cyclists, drivers, and adventurers. The Pass-Thru+ charging, a professional feature, can completely bypass the internal battery and allows the device to operate in extreme cold (-20 °C).