... might run out of power ! 2:High capacity li-ion battery cell (2800 mAh ) increases devices usage time . 3 ... from a USB socket such as iPod , iPhone ,Cell phone and MP3 player . 4:Compact size , ... Supply (included )conveniently. 7:Built-in battery tester button with battery level LED indicator . 8:Power On ... to save battery when not in use . Compatible with: iphone 4,iPhone 3G/3GS, ,Cell phone , and ...