"Nathan® Pinnacle 18 ounce Insulated Soft Flask: The Nathan® Pinnacle 18 ounce Insulated Soft Flask is a handheld hydration bottle built for runners, hikers, and trail athletes who need reliable fluid access without the bulk. At 18 ounces (532mL), it holds enough for long runs and extended trail days, while the insulated construction keeps your drink noticeably cooler longer - a real advantage when you're hours into a warm-weather effort. Weighing just 3.35 ounces (95g), it carries light enough that it won't disrupt your natural arm swing, making it an easy choice for anyone who prefers handheld hydration over a pack or vest.The proprietary ExoSpine™ interior gives the soft flask a structured hand feel, so it maintains its shape and stays easy to grip even as it empties - no more collapsing flask frustration mid-run. An ergonomically designed hand strap with breathable wicking mesh keeps the flask secure without requiring a constant grip, which matters during longer efforts when hand fatigue becomes a factor. A small expandable stash pocket holds gels, keys, or other essentials, reducing the need for additional gear. The soft flask removes easily for straightforward refilling and cleaning, and the bite valve delivers quick, controlled sips without breaking stride.Why Our Fit Experts Love It""I took the Pinnacle Flask on a two-hour trail run and appreciated how the ExoSpine™ kept it from collapsing in my hand as it emptied. The stash pocket held my gels without bouncing, and the insulation kept my drink noticeably cooler than a standard soft flask would have."" - Sean, Road Runner Sports Fit Expert, Chula Vista, CAWho It's Best ForThe Nathan® Pinnacle 18 ounce Insulated Soft Flask is best for runners, hikers, and outdoor athletes who prefer handheld hydration for long runs, trail days, and warm-weather training. It suits anyone who wants a structured, easy-to-grip flask with on-the-go storage for gels or keys. If you're looking for a water bottle that stays comfortable in your hand without constant squeezing, this is a solid choice. VIP Family members can take the Pinnacle 18 ounce Insulated Soft Flask for a 90-Day test drive with our Perfect Fit Guarantee."