This thing uses a fuel cell and it is a battery extender, its not any entirely new idea, but this particular iteration should be a lot healthier for the environment if and when you ever decide to dispose of it. And the battery life extensions, are simply amazing.
Here are the numbers, for a smartphone, you can get an additional 20 hours, for any other phone, 30 hours, or for a media player, up to 80 hours! That quadruples the life of most media players.
There are several tips available so they should have one for your device, I assume those are sold separately. This thing is both UI and DOT approved, so its good to use, even on the go, and you can pick it up for $30.