According to CNET news Many major US airlines have announced restrictions on so-called smart luggage out of concern their lithium ion batteries may pose a fire risk.

Smart luggage tends to contain a USB port for charging devices, GPS to track the bag’s location, remote locking and built-in weight sensors. Some even sport a motor to propel the bag for ease of movement through an airport.

These features require power that is often supplied by built-in lithium ion batteries, which contain highly flammable liquid. Worried the batteries could cause a fire in the cargo hold that would go undetected, airlines are instituting new rules that require fliers remove the batteries when they check their luggage and carry them into the passenger cabin.

“Beginning Jan. 15, customers who travel with a smart bag must be able to remove the battery in case the bag has to be checked at any point in the customer’s journey. If the battery cannot be removed, the bag will not be allowed,” American Airlines said in a statement on Friday. Delta and Alaska soon followed suit with similar policies on their flights.

In the past couple of years, the use of lithium ion batteries has been linked to fires and spewing smoke in a slew of products, including Samsung’s now-canceled Galaxy Note 7, hoverboards, and Boeing’s 787 Dreamliner.

The Federal Aviation Administration issued a warning about the batteries last year, urging airlines to examine the risks associated with transporting lithium batteries as cargo, including “the potential risk for a catastrophic hull loss.” The alert covered batteries being transported as components and not those already inside devices such as laptops, tablets, phones or hoverboards.

However, many bags have batteries that can’t be removed, and that has smart luggage makers like Bluesmart worried.

“We are saddened by these latest changes to some airline regulations and feel it is a step back not only for travel technology, but that it also presents an obstacle to streamlining and improving the way we all travel,” Bluesmart told CNN.