Pen Power 8,000 mAh Mini Power Bank
Last but not least, we wanted to recommend something a little different from everything else on our list. The Aibocn Pen Portable Mini Power Bank isn't slim, but it's not big either. It's about twice as thick and long as a bottle of chap or lipstick, yet packs 8,000 mAh of battery power inside. It's one of the smallest chargers around.
You can easily throw this in your pocket, purse, or the pen-slot in a backpack and have power ready for when you need it.
With 8,000 mAh of power, you can top of almost any phone twice, and it even offers 2.1A fast charging for some Android phones. It's a nice little device you'll be glad to have when you need it, and at $10 its an impulse buy.