External battery for iPhone 4

Function and features:Enhance iPhone 4 Signal;Power checnk and indicationPower switchStandby time: up to 230 hoursTalk time: up to 6 hoursInternet use: up to 5.5 hours on 3G network and up to 8 hours on Wi-FiAudio playback: up to 30 hoursVideo palyback: up to 8 hoursWeight: 125Gcapacity:1900mahCell type:Lithium-ion batteryOutput:5VOutput current:500 mACycle life:500 times..

External battery charger case for iPhone 4G