I bought this after much research to find the right power source to keep my iPhone in GPS mode while driving. A charge of 1000m is needed and most devices deliver about half that - so the phone in GPS mode on a lesser-powerful charger will actually run out of juice while plugged in. This charges fast and keeps it charging while in use - and this was all while driving a 1980 Cadillac half way across the country. Highly recommend. And the price is phenomenal.