When you're running on warm summer days, it's nice to have a cold, refreshing drink. With the Nathan Insulated Soft Flask with Bite Top, you'll have 18oz of cool refreshment as you run. Its insulated design keeps fluids cooler 38% longer than non-insulated soft flasks so you can expect a refreshing drink even when you're several miles deep. And conveniently, the flask is compatible with all Nathan hydration vests.