Collapsible flasks solve the problem of what to do with an empty bottle during a long run. Hard bottles stay bulky whether they're full or empty, which means they take up the same amount of space in your vest pocket or hand the entire time. The Quick Stow Flask collapses down once you drain it, shrinking small enough to fit in a running short pocket or tuck into the bottom of a vest without the bulk of a rigid container bouncing around. That matters on trails where you're carrying multiple flasks or trying to minimize weight as the run progresses and you empty bottles at aid stations.

The flask holds seventeen ounces when full, which works for shorter efforts or as supplemental capacity when you're carrying a larger reservoir in your vest. Volume markings printed on the side show both ounces and milliliters, which helps when you're mixing electrolyte powder and need to hit specific ratios without guessing. The one-piece silicone bite valve self-seals after each drink through compression rather than a spring mechanism, so you can tuck the flask back into your vest without worrying about residual drips soaking your phone or nutrition. The bite valve uses the same design as CamelBak's reservoir systems, which means the flow rate is consistent with what you're used to if you already run with their hydration packs.

CamelBak sized the flask to fit the front pockets on their running vests, but the collapsed profile works in other brands' harness systems too. When empty, the flask folds flat and the cap sits flush against the body, eliminating the rigid tube and valve assembly that sticks out on some collapsible bottles and catches on vegetation or gear. The cap twists off completely for filling and cleaning, and it goes on the top rack of the dishwasher without degrading the seal or leaving a plastic taste in the water. The soft material is quiet in vest pockets, unlike rigid plastic bottles that rattle against other gear with every stride.... Read More