The Nathan Speed 2 Hydration Belt is good for a run of at any distance. Every runner will benefit from proper hydration, and consistent sipping is key to maximizing the benefits. The Nathan Speed 2 Hydration Belt features molded holsters that carry Nathan’s 10 oz. Flasks of the go in and out easy, one-handed removal and replacement of Flasks. Ideal for carrying water, sports drinks, or energy gels, Nathan’s 10 oz. Flasks won’t leak, slip, or eject from holsters. The bottom line is this is great for race day or training for that 10k all the way too marathon.