Reserve Convertible is a slim, protective case with a detachable lithium-ion polymer battery pack that delivers 5 watts of power. To look at it, you"d never guess so much power could fit in such a slim profile.Charge your Galaxy S III while you carry it, or detach the battery pack to travel light. While it"s taking care of your battery, the case is taking care of the back and sides of your phone, with convenient access to connectors and controls.The Reserve Convertible case is power to go, when you want it, and less bulk, when you don"t.