High-tech, backless, ventilation-optimized carrying device for hydration systems and other essential items on shorter trips. With enough space for a hose, some tools, and a 1.5-liter hydration system, it features a very thoughtful system that offers an extra level of comfort called the Venti Flap: increase the distance at the back for ascents and tighten it at the hips for descents, simply by pulling a cord.