The Camelbak Motherlode Hydration Pack 40L with 3L Mil Spec Crux Reservoir I perfect for multi-day usage! Equipped with a multitude of design features to enhance your overall experience such as, four-zipper full clamshell openings on main compartment, three lash points in main compartment and side-release buckles for quick release from shoulder harness, this superior rucksack is a must-have essential. Take on your next adventure knowing that your hydration is looked after with the zippered back panel access to make loading a full reservoir into the hydration compartment easy and a Low Rider™Reservoir compartment to shift weight down on the back for comfort.