iPhone batteries aren’t the best for situations where you will be doing constant texting and calling, etc.
This case is the PowerSkin with a built-in battery. It’s for the iPhone 4 and iPhone 4S. It’s a cool case, because it serves a double-duty as a protector of your iPhone and an extra battery pack.
Usually, we avoid cases for our iPhones. It adds a bit of bulk. Bulkiness is not fun to carry around. At the very least, there is a tradeoff for this extra bulk. It’s great to have the extra battery life. It comes in handy when you are away from a power source, which is actually quite common when traveling.
Check it out. Here.