The Osprey HydraJet Hydration Pack delivers all the same greatness as your favorite Osprey bag, but now in a smaller, child-specific size. It has 12 liters of volume inside, perfect for packing layers, maps, and snacks for the trail; everything they need for a days worth of adventure. And an Hydraulics reservoir with 1.5 liters of room has also been included inside its own external sleeve, to make sure your kid stays hydrated under the sun.