There are precious few battery packs out there with USB-C power delivery, and this 26,500mAh model from Aukey is one of the biggest and most affordable we’ve seen.
In addition to the two standard USB output ports, the USB-C port works as both an input and high-speed output port that can charge a 12" MacBook at full speed. It’s pretty huge, but 26,500mAh should be enough juice to power your devices for hours or days on end. Just be sure to use promo code FORMOMP7 at checkout to get it for $56.