If you want to bring a tumbler or thermos on an international flight from the U.S., it must be empty and is allowed on board.

Conditions for Bringing on Board

• The tumbler must be empty: The TSA allows empty tumblers or thermoses to be brought on board. If it contains liquid, it may be confiscated or discarded at the security checkpoint.

• Allowed regardless of material: Empty tumblers made of stainless steel, plastic, glass, etc. are permitted on board.

• Recommended to separate during security check: During security checks, it is helpful to take the tumbler out of your bag and submit it separately.

Liquid Carry-On Regulations

• 3-1-1 Rule: Only liquids in containers of 3.4 ounces (100ml) or less are allowed in carry-on luggage, and these must be placed in a clear quart-sized zip-top bag.

• Filling the tumbler with liquid after security is allowed: After passing through security, you can fill your tumbler with water or drinks from water fountains or shops in the airport.

Precautions When Using International Flights

• Check the regulations of the destination country: Some countries may have specific regulations regarding the import of tumblers or thermoses, so it is advisable to check the customs and security regulations of the destination country in advance.

• Check the airline's policy for carry-on: Some airlines may have their own policies regarding the use of tumblers, so it is advisable to check the airline's policy before boarding.

Summary

• Empty tumblers or thermoses can be brought on board international flights from the U.S.

• If it contains liquid, it may be confiscated at the security checkpoint, so caution is needed.

• After security, you can fill your tumbler with drinks at the airport.

• Check the regulations of the destination country and airline in advance to avoid unnecessary inconveniences.

Wishing you a safe and enjoyable trip!