The most popular and fastest selling hydration belt in the US. It works because it is very comfortable and completely relieves you of the typical bottle bounce found with other hydration belts. The weight distribution is ideal and the 7 ounce flasks let you mix and match your fuel. A total of 28 ounces is enough to get you through most workouts. Whether you're training for a marathon or trail running to stay in shape, The Endurance is the perfect piece of gear to take on the road. Used by Ironman champions around the world, it will work for you too.