Rev up the intensity of your trail run or mountain bike ride without uncomfortable pack jiggling slowing you down. The smartly designed Osprey Rev 12 Hydration Pack feels like a natural extension of your back, staying securely in place while you bounce up and down the trail. The BioStretch shoulder harness and waist belt are designed to lie flat against your body and follow your movements like a piece of stretchy clothing, eliminating uncomfortable rubbing and chafing. Two sternum straps keep the pack from swinging side to side, and can be adjusted or removed to suit your preferred position and pack fit. Quickly tighten or loosen the waist belt on the fly with the easy to operate ErgoPull closure, and control the volume of your load by cinching down the bungee cord webbing on the front of the pack. The mesh covered back panel, shoulder harness, and waist belt keep air flowing while you're working up a sweat barreling up and down the trail. The Rev 12 comes equipped with a lightweight 2. 5 liter hydration reservoir that fits in its own dedicated compartment, and is designed to prevent water from sloshing around while you move. A magnet on one of the sternum straps holds the drinking tube bite vale so you can quickly sip and then get the tube out of the way. The pack also includes a a zippered expansion water bottle sleeve for holding additional water or a non water drink of choice, and it can be stashed away if you don't need it. Use the slew of additional pockets from a large zippered front pocket to the drop down, removable media pocket on one of the shoulder straps to organize your supplies and keep them ready at hand so you won't have to stop. From its overall design to its pocket placement, the Rev 12 is all about keeping you moving without anything holding you back. Working hard will never have felt so good.