The "USB 2" port on the BootstrapSolar/Chi-qoo battery pack can be upgraded to a Dedicated Charging Port, which will allow many modern devices (including many Android phones as well as the iPhone 4S) to charge much faster, or support devices that may not otherwise work.
However, if you do perform this upgrade, you may only use one USB port at a time. Charging two devices simultaneously from both ports can generate excessive heat and damage the electrical circuits and battery. While the circuits should go into thermal shutdown in the event of excessive heat, should this last line of defense fail, the device could pose a fire risk.
Perform this upgrade at your own risk.
To upgrade the "USB 2" port to a Dedicated Charging Port, simply plug the supplied jumper onto the two pins behind the USB port on the USB Charger Circuit: