High-energy activity requires keeping hydrated. That's why the Viper 13 Rucksack comes equipped with an integrated 2.5-litre Hydraulics LT Reservoir, so you can push yourself to the limit. The reservoir is accessed via an asymmetric zip for quick and easy refills. The reservoir incorporates two chevron welded baffles to help maintain shape when full and limit sloshing from the water. Osprey solved the wandering hose' issue by placing a magnet in the pack sternum strap and bite valve. This holds everything neatly in place when not needed; yet ensuring quick and easy access when it is.The ventilated AirScapack panel and BioStretch harness keep you cool in hot conditions whilst still offering flexibility for movement without restriction. The LidLock attachment provides a quick and secure attachment point for your helmet without taking up space inside your pack. Gear and bike tools are easily organised and carried within the quick access internal compartments. The front compression pocket provides an ideal space for bulky additional items or used as a handy place to stash wet items on the go. Lower side compression means that your load is secure over the roughest of terrain. A removable webbing hipbelt allows you to shed extra weight if you're really counting the grams. Reflective graphics and LED light attachment help to keep you visible for when the weather turns or night falls.