I want to buy one too,
From what I found, the FAA (Federal Aviation Administration) permits Lithium ion batteries of up to 100 watts hour (Wh). The Wh you get it with this formula: Wh = V*Ah.
This battery is a 7800 mAh = 7.8 Ah.
The volts, I believe is a 5 V
So it's Wh is = 7.8*5 = 39 Wh
So according to this info it's good for air travel: https://www.faa.gov/about/office_org/headquarters_offices/ash/ash_programs/hazmat/passenger_info/media/airline_passengers_and_batteries.pdf
Still it's a good idea to contact your airline.
Date published: 2018-01-09