This hydration-ready training pack has the largest internal volume of our lightweight and breathable Aerios series, as well as an external stretch-mesh kangaroo pocket. Offering our AeroForm backpanel for maximum airflow and comfort, a modular bungee system for compression or cargo hauling expandability, and a modular waist belt that can be positioned higher on the abdomen for superior bounce control. Lightweight, body-hugging hydration pack, Built for use on the Paths.