The big reason to think twice before buying a smart ring? Their batteries.

Tech YouTuber Daniel Rotar recently experienced a wearable worst-case scenario: The tiny, flexible battery in his Samsung Galaxy Ring began to expand, squeezing his finger while waiting to board a flight in Frankfurt.

The situation was painful and panicky, but thankfully temporary, he said in a follow-up video — a trip to a local hospital saw medical staff remove the ring without incident.