Yoobao 12,000 mAh Slim Battery Pack
As a perfect middle ground, we found a nice 12,000 mAh slim portable battery charger. It's more than a 10k without being too thick, and it's not massive like the 20k we mentioned earlier.
With 12,000 mAh of power you can top off most phones around 4 times. This little battery pack is a hair thicker than the iPhone X, and has two USB ports so it works with any device that takes a USB cable. Give it a try.