With 3 liter hydration capability and nearly 15 liters of cargo carrying capacity, the Nathan Water Bottles X-Treme Hydration Pack is perfect for runners, cyclists, and hikers who must pack for the unexpected in the great outdoors. This comfortable pack carries a load quietly without infringing on your natural range of motion. A series of clever stash pockets for glasses, GPS, helmet, and gels make this well-designed pack a favorite with ultra-distance athletes. Mother Nature can be fickle. Better safe than sorry with the Nathan Water Bottles X-Treme Hydration Pack.