Airplane Regulations
In the current version of the fin, the battery is embedded into the device and is not removable. The power over time value for a Boost Fin Plus is 77.7 Wh (watt-hours) which does not exceed the carry-on limit of 100 Wh (learn more here Boost Fin Specs).
Lithium batteries with more than 100 Wh may be allowed in carry-on bags with airline approval. One spare battery, not exceeding 300 Wh, or two spare batteries, not exceeding 160 Wh each, are permitted in carry-on bags.
Tip: Be sure to take out the screwdriver if you plan to travel with your Boost Fin in a carry-on bag. It's recommended to put the screwdriver in the baggage.