"Nathan® QuickStart 3.0 4L SF: The Nathan® QuickStart 3.0 4L SF is a lightweight hydration vest built for runners who need reliable access to fluids during training runs and race efforts. Two included 14 oz soft flasks sit in dedicated Power mesh drop-in pockets, so you can grab water mid-stride without breaking rhythm. At just 7.45 oz without flasks, the vest stays light enough that it won't interfere with your natural movement, even as the miles add up. With 4L of total storage capacity, you'll have room for fuel, layers, and essentials on longer efforts without the bulk.The Power mesh pocket construction keeps soft flasks secure while making them quick to retrieve, and reflective detailing improves visibility during early morning or post-sunset runs. This unisex vest accommodates a broad range of athletes, from those logging daily training miles to competitors managing hydration strategy on race day. The combination of included flasks, accessible storage, and reflective elements makes the QuickStart 3.0 4L SF a practical, no-fuss option for runners who want hydration and visibility handled in a single piece of kit.Why Our Fit Experts Love It""I wore the QuickStart 3.0 4L SF on an early morning long run before sunrise, and the reflective detailing gave me real confidence on the road. The soft flasks were easy to pull and replace mid-run, and I barely noticed the vest's weight even as the miles added up."" - Sean, Road Runner Sports Fit Expert, Chula Vista, CAWho It's Best ForThe Nathan® QuickStart 3.0 4L SF is best for runners who need quick access to hydration and enough storage for fuel and essentials without carrying excess weight. It works well for those training in low-light conditions who want built-in reflective visibility, and it suits both daily training and race day efforts. If you're logging long runs or need a lightweight hydration vest that's ready to go right out of the box with included flasks, this is a practical choice. VIP Family members can take the QuickStart 3.0 4L SF for a 90-Day test drive with our Perfect Fit Guarantee."