Detachable Battery Case, Why Is This Just Happening?
The Third Rail iPhone 4 battery case takes the familiar idea of a charging case and makes it practical.
Batteries, for the most part, are removable and replaceable. Unless you're an Apple product. The Third Rail battery case takes this novel idea and runs with it. The base case ($39.99) and the battery ($59.99) can be purchased separately or together ($89.99, you save $10 purchasing them together.) The case itself is a slim matte black case. It reminds me of brushed aluminum Apple uses if it were painted black. The 1250mAh smart battery can be attached to the case and even stacked four deep. I can't imagine that feeling to comfortable in the pocket.
All of this transferred energy passess through the "Third Rail" system, which utilizes gold rails to transfer energy and create a stackable energy hub. The ability for the batteries to charge other devices via a micro USB port puts the stackable battery ability to good use. With four batteries stacked at once, you can charge your iPhone and all your other gadgets at once. Or your friends' Android Phones, lord knows they're battery hogs.
Third Rail promises that the smart batteries are "future proof" and will be compatible with future case designs, which prevents you from having to buy new batteries every time. Also, it means a whole new case does not need to be purchased if the batteries die like in other power cases with built in battery solutions.
This simple and smart solution to power hungry mobile phones is refreshing to say the least.
Source: Third Rail