Osprey entered the ultralight backpack game this year with its Rev series backpacks, and the Rev 6 Hydration Pack is the second lightest backpack in the line, made to stay put during fast moving trail runs and mountain bike loops. Larger and not as minimalist than the Rev 1. 5, the Rev 6 includes a zippered front pocket to hold larger items like a rain shell, trail maps, or bike supplies, and a zippered expansion water bottle sleeve for holding additional water or a non water drink of choice. The lightweight 1. 5 liter reservoir that's included with the pack is specially designed to prevent water from sloshing around while you're bouncing up and down the trail, and the backpack itself is designed to fit snugly and follow your movements to prevent irritating jiggling and uncomfortable chafing. Not just one, but two sternum straps keep the pack securely in place, and can be adjusted to your preferred position. One includes a magnet that conveniently holds the drinking tube's bite valve so you can quickly sip and then get the drinking tube out of the way. Two pockets one on each shoulder strap hold energy gels and your cell phone, and stretch side pockets and the front bungee web accommodate additional supplies. The Rev 6 is designed to sit higher on your back, and doesn't use a hip belt at all since the shoulder harness supports the entire load. The mesh covered back panel and shoulder straps keep air flowing while they stay securely in place making the pack feel like a natural extension of your back. With the Rev 6, working up a sweat barreling through trails will never have felt so good.