18,000 mAh is a lot. Consider that your iPhone 6 has a 1,810 mAh battery, so the Power Vault 18000mAh Portable Battery Pack would be able to charge it almost 10 times over before it needs its own top up. That’s a heck of a lot of electricity to carry around in a 6? × 3?x .4″ package (yes, not even half an inch thick). Better yet, it’s got two USB ports, so you can juice up two devices at once. One of the ports outputs 1A, while the other kicks out 2.1A. And all this in a $29,99 package? It’s practically a steal!