These devices typically contain a cylinder of compressed nonflammable gas. Some models also contain a small explosive charge (squib) to release the cylinder contents.
Though allowed in checked baggage by international (ICAO/IATA) regulations, these devices are not allowed in baggage in the U.S. unless the gas cylinder is empty and there is no explosive charge.
Though not restricted as a hazardous material when the gas cylinder is empty and no explosive charge is present, airport security screeners may still want to examine the gas cylinder to ensure it is empty.
For models containing Li-batteries, see PackSafe battery guidance