A 10,000 mAh travel battery has USB-C input/output, one USB-A port, and a clear remaining-charge display. Flat edges pack neatly beside a phone without the bulk of a high-capacity brick.
The USB-C port accepts and supplies up to 20W Power Delivery; USB-A supplies up to 18W. A 30cm USB-C to USB-C charging cable is included in the box.
Check current airline rules, protect the terminals, and keep the battery away from excessive heat.