The iPhone 4 has been the favorite smartphone for accessories over the years. PowerSkin is the only one that has created battery cases for various Android running smartphones. The PowerSkin is a protective, recycled and anti-fingerprint silicone rubber case with a built-in 1500mAh battery, enough to double your Android handset's battery life. Yes, every single PowerSkin battery case no matter what Android smartphone model it was designed for, has exactly the same battery capacity built-in. The PowerSkin battery cases are available for the HTC Evo 4G - myTouch 4G - Desire HD - Inspire 4G - ThunderBolt, Motorola Droid X/X2, Samsung Galaxy S 4G - Vibrant - i9000 - i9003 and last but not least the Nexus S 4G. These are all available right now via Amazon for $59.99.