Stay hydrated on the go with the CamelBak Hydrobak 50 Oz. Hydration Pack. The reservoir has a 1.5-liter capacity for up to 1.5 hours of use and fills externally for fast and easy refilling. The diamond-mesh back panel promotes airflow to keep you cool, and the lightweight mesh harness distributes weight comfortably. The pack's essentials pocket offers easy access to necessities, while front and back reflectivity offers increased visibility in low-light conditions.