eBay has the 2600mAh USB power bank external battery key chain charger for only $4.67 shipped. That’s $2 less than Amazon’s current listing and the lowest price we could find for them. It has a built-in 2600mAh high capacity rechargeable li-ion battery that carries an input of 5V 1A. and an output of 5.3V 1A. It comes in your choice of 6 colors and it includes a charging cable.