The MiLi Power Spring 4 case for iPhone 4 does more than protect your device. Inside the case is a 1600mAh battery that can increase your talk or internet time by about 6 hours, or music by 36 hours, or video by about 10 hours. The case has a glossy black finish with a one-piece design; the top has a bendable flex-top that makes popping in the iPhone 4 easy. It comes with a USB cable that charges the case’s battery and charges and syncs the iPhone 4 at the same time. The MiLi Power Spring 4 is licensed and certified by Apple for iPhone 4 and is available at Richard Solo for $79.95.