The myPower MP1280 battery (which also comes in red and white!) is a unique battery that DOUBLES the usage time of your iPhone 4 or 4S and also serves as an attractive protective case. It works with the Sprint, Verizon, and AT&T versions of the iPhone 4 and 4S (unlike some iPhone batteries, which only work with the original AT&T model). Customers love it:
The battery/case adds very little to the phone in terms of weight or dimension, but has at least doubled the time required between charges.myPower iPhone 4/4S Battery links:
Nice protection for the i-phone, the extra battery is awesome! My wife has a Droid and has to charge her phone much more frequently than the i-phone with this battery pack.
Just what I needed. The battery life has doubled. It is light and not so boxy and bulky as other extended battery packs. Good basic bumper coverage.