Overview: This backup battery is specially designed for iPhone 4. Fashion designed, black color, this backup battery looks elegant. The sleek backup battery power pack snaps inconspicuously onto the back of your iPhone. Adding only a few milimeters of thickness, but this backup battery can more than doubling the battery runtime of your iPhone. Battery Type: Li-ion battery Compatibility: iPhone 4 Standby Time: up to 390 hours Talk Time: up to 6.5h on 4 G Internaet Use: Up to 6.5 hours on 4G, up to 8 hours on Wi-Fi Audio Play: up to 31 hours Video Play: up to 9 hours Specification: Weight Approx:78g Size Approx:13.7 x 6.2 x 1.8