The ExoLife Galaxy S4 battery case is a sleek, protective exoskeleton for the Samsung Galaxy S4, outfitted with a rechargeable external battery to give your Galaxy S4 the extra power that you need. The ExoLife serves two functions: Power and Protection. The lithium-ion battery inside the ExoLife virtually doubles the battery life of your Galaxy S4 so you can talk, surf, watch and play longer. And there is no need to sacrifice the beauty of your Galaxy S4 with some clumsy looking case - the hard-shell casing of the ExoLife wraps snugly around your Galaxy S4 to give it maximum protection while enhancing the look and feel of the Galaxy S4 itself.