Cordless hair tools were once a boon for travelers, with their portable, bulk-free designs that didn't require a special adapter when visiting overseas. Now, new guidelines from the Transportation Security Administration (TSA) no longer permit cordless curling irons, hair straighteners, and more in checked bags as they can catch fire in the cargo hold (the gas cartridges and lithium batteries that power them are highly flammable).
But the TSA said their counterpart has restrictions: cordless hair styling tools that are powered by lithium metal or lithium ion batteries or gas or butane fuel are only allowed in carry-on bags. That's so that passengers or flight attendants can react if they start to overheat in the cabin. If they overheat or combust in your checked bag in the cargo area of a plane, it may take a while for anyone to notice.