KMASHI's 10000mAh external battery charger is slim enough that you can carry it around in your pocket and charge your phone at the same time, as long as you aren't bothered by the prospect of walking around with a little bulge. Last month we saw it available on Amazon for $9.50 after a coupon code. Now it's back, and by entering JAK3JCUV at checkout, you can get it for $9.40 instead.
Yeah, a 10 cents difference isn't all that much. But keep in mind, we're talking about getting an external battery pack for under $10 bucks. Even if you don't need something slim, this is still a cheap way to recharge a modern smartphone three or four times before having to return to an outlet.
This backup charger comes with two USB ports, so you're not stuck powering one device at a time. One will get 5V/2.1A, while the other is left with 5V/1A. The hardware is 5.5 inches long. As for width, you're looking at 2.5.
If all of this sounds just dandy, then you might want to click the link below.