GreatShield PowerTank External Battery Charger
Where to buy:
http://www.amazon.com/dp/B00EEHNNKY/k...
Power and Speed
The PowerTank could charge up to two devices simultaneously with its dual charging port, one at 5V/1A and one at 5V/2.1A at maximum of 3.1A total output, making it perfect for the power-hungry smartphones and tablets.
Built to Last
The PowerTank comes with build-in short circuit, over charge, and over-heat protection. The PowerTank uses rechargeable lithium polymer battery supporting more than 500 charge cycles during the course of the PowerTank's life.