|It is not only a iPhone case, this iPhone Case($25) built-in a high capacity li-ion rechargeable battery. The sheepskin case keeps the edges of your phone protected from wear and tear, while the battery provides you with a charge of juice when your battery is running low. You can charge the battery via the USB. Unfortunate it is just for the 1st Gen iPhone and iPod Touch. I don't know that would you check out it, but it is a really good idea. I think some famous iPod cases may consider this idea.