Featuring a USB 1A charging output with 2,4000mAh capcity you can fast-charge nearly any smartphone or MP3 player back to full capacity with power to spare! The GMP2K serves both as a battery extender to your power hungry mobile devices, also a battery charger when conventional AC outlets are not available. It is compatible with most smartphones such as iPhones, as well as MP3 Players,handheld gaming systems, etc.