Whether we're supporting our own long run or facing long stretches between aid stations at our next ultra, we kit up with the Osprey Duro 15L Backpack. With a 2. 5-liter bladder and designated spaces for gels, bars, creams, layers, headlamp, and more, this vest keeps us stocked, while the stretch mesh build hugs our form and the adjustable vest-style harness pulls in our load for a stable, distraction-free carry as we stride up switchbacks, along ridgelines, and down through valleys.