I plan to ship via Yu-Yu Mercari Bin's Yu-Packet Post Mini. [Two-in-One Device] Not only a transmitter, but also a receiver. Even with non-Bluetooth earphones, TVs, or car audio systems, you can use this product wirelessly. [Call Function] With a built-in microphone, hands-free calls are possible in RX mode. By connecting to your car's AUX terminal, you can enjoy music from smartphone apps in your car and make hands-free calls. [Bluetooth 5.1] Equipped with Bluetooth 5.1, it achieves low-latency and stable connections, with a communication range of up to approximately 15 meters (without obstacles). Delays are minimized, allowing you to comfortably enjoy dramas and movies. [Easy Operation & Multi-Device Compatibility] The transmitter/receiver can be switched simply by operating the switch on the main unit. The simple design with only one button makes it easy to operate. Also, it uses a 3.5mm AUX plug, making it applicable to devices with a 3.5mm audio output jack. [Long Playback & Small and Lightweight] It has a built-in 150mAh battery and can be used for about 5 hours in transmitter (TX) mode and about 8 hours in receiver (RX) mode. Weighing only 10g, it is very lightweight and can be easily carried in your pocket.