Third Rail Slim Case with Slide-On Smart Battery for iPhone 4/4S

Got this Third Rail slim case and slide-on smart battery for the iPhone 4 or 4S. It's a pretty cool setup because you can just slide the battery part on when you need a charge and take it off when you want to keep the phone slim. The box is a bit worn but the stuff inside looks fine. Good if you're still rocking an old school iPhone and need some extra juice.