The big difference between the iPhone 4 and the Galaxy S is that the Galaxy S has a removable battery while the iPhone 4 hasn’t. If your Galaxy S battery is empty, it doesn’t have to be a problem because you can just put a new fully charged battery in it and you are good to go. Luckily there is also a solution for the iPhone 4 users, the Mili PowersSpring 4. The Mili PowerSpring 4 is a extended battery pack for your iPhone 4 that will double the lifetime of your iPhone battery.

The Mili PowerSpring 4 starts shipping today for £54.99 (or $85 on Amazon). It includes a 1600mAh capacity Li-Pol battery, and they claim the Mili PowerSpring 4 is the world’s thinnest iPhone 4 battery pack.

Source [Engadget]