The CamelBak Crux 3L Reservoir is hydration for the long haul. (This bladder fits best in larger daypacks or full-size backpacks.) Its large lid makes filling simple - even from tough sources like water fountains. (Pro tip: it also makes cleanup a breeze.) Its Polyurethane construction features Hydrogaurd technology to stop bacterial growth in both the reservoir and tube. The tube has a Big Bite Valve for fast-flowing, drip-free hydration, and an on/off lever for added leak avoidance.