iPhone 4 Slim Case Features Slide-On Battery

The Third Rail System includes a Slim Case for the iPhone 4 with a slide-on Smart Battery that allows you to add power when you need it and remove it when you don't.

The Slim Case is a sleek, everyday protective case with a high quality, soft-touch feel. The Smart Battery can also function as a standalone backup battery to power other devices via USB Adapter (included).


Feature:
● Add power when you need it- remove it when you don't
● Includes the Slim Case for iPhone 4 and a Smart Battery
● Use Slim Case as an everyday protective case
● Thinnest battery enabled case on the market
● Use Smart Battery as an universal external charger or slide onto Slim Case for additional power for your iPhone 4
● Check your power capacity with the push of a button

You can purchase the system for $89.99.

[via 9to5Mac]