Ideal for fast paced pursuits the osprey viper 9l hydration pack offers ample space for essentials alongside a 25l hydraulics reservoir system for on the go refreshment with plenty of pocket space spread across the pack and bike light and helmet attachment points this pack is designed with cyclists and runners in mind the ventilated and breathable back system ensures constant cooling with an adjustable biostretch harness for cooled cushioned comfortactivityrunning cycling fitnessadju