When going for a record car-to-car time, we load the essentials in Mammut's Aenergy 18L Daypack. The running-vest-inspired shoulder straps feature 2 pockets to stow soft flasks for handy hydration that won't slow us down, while the lightly padded back panel keeps our carry comfy, not weighted. As the trail steepens and our pace quickens, the bungee sternum strap stretches with our breathing, letting our lungs expand freely. In addition to a speed-minded design, this pack features a partially recycled construction that keeps our carbon footprint light.