Bluetooth Audio Transmitter/Receiver LBT-ATR01BK ¥4,213 (Tax included) This is a transmitter that allows you to make non-Bluetooth products Bluetooth-compatible. By connecting it to a Bluetooth speaker, you can efficiently listen to the TV's sound through your speaker, or enjoy in-flight entertainment with your Bluetooth headphones without worrying about the headphone cable on a plane. It's very useful. I have two of these, and since I'm using one less frequently, I'm putting it up for sale. Below is the official website text: https://www.elecom.co.jp/products/LBT-ATR01BK.html This is a Bluetooth audio transmitter/receiver that allows you to listen to in-flight entertainment or TV audio with your usual wireless earphones/headphones. The two φ3.5mm plugs each rotate, so it supports both the φ3.5mm dual jacks in airplanes and the φ3.5mm headphone jacks on TVs. You can use it while charging, so you don't have to worry about the battery level. Thank you for looking.