The Muon is designed for hikers who value light weight- the materials have been chosen, and the structure has been designed to avoid unnecessary weight. *Note!* The hydration bags and bottles seen in some images are not included. Thanks to the roll-top opening, in addition to light compression straps, the backpack also effectively has a top compression system: you simply roll the opening as much or little as today's cargo requires. The lower compression straps also serve as sleeping pad straps. The lightweight but durable ripstop fabric is protected against UV radiation, meaning it shrugs off extended exposure to sunlight. The ergonomic Tri-Flex carrying system includes shoulder straps, lumbar support, and a hip belt that all adapt exceptionally well to the shape and movements of your body. This model boasts a carrying system best suided for me. - Compatible with a separately purchased max. 3-liter hydration bladder - The hip belt can be conveniently tightened by pulling the straps