Lithium metal (e.g. coin cells) or Lithium-ion (e.g. smartphones). Both - when installed in a device - can be transported in checked luggage though: https://ww

Lithium metal (e.g. coin cells) or Lithium-ion (e.g. smartphones). Both - when installed in a device - can be transported in checked luggage though: https://www.iata.org/contentassets/05e6d8742b0047259bf3a700bc9d42b9/lithium-battery-guidance-document.pdf https://www.iata.org/contentassets/05e6d8742b0047259bf3a700b... IATA actually has a document specifically addressing tracking devices: https://www.iata.org/contentassets/05e6d8742b0047259bf3a700bc9d42b9/lithium-battery-guidance-document-2021-for-pharma-en.pdf https://www.iata.org/contentassets/05e6d8742b0047259bf3a700b... My reading of that document indicates that an AirTag should be fine, as low-powered wireless communication is allowed (page 9, item 3).