【Bluetooth 5.1 Audio Adapter】Bluetooth 5.1 signal stable transmission does not lag, listen to music and call more smoothly 【Multi-Device Expansion】Bluetooth receive/transmit mode and optical/coaxial digital audio to analog audio. U disk/AUX/TF audio input and multi-device expansion interface to meet different needs. 【Infrared Remote Control】Equipped with infrared remote control for easy operation , anytime, anywhere, anyway you want 【Lossless Sound Quality】HIFI shocking lossless sound quality, clear and no noise, enjoy good music, naturally feel good 【Built-in 800mAh Battery】Built-in 3.7V/800mAh battery, can be used continuously for 7 hours, standby time up to 300h 【Widely Use】A4 is a Bluetooth 5.1 Receiver and Transmitter audio adapter,which it can compatible with all mobile phone or tablet,also can work on the Car,computer,tv,older version speaker etc.Whether you are studying, living or working, share audio at any time Specifications: Product Name: Multifunctional Bluetooth Audio Adapter Product Model: A4 Bluetooth version: V5.1 Product material: Aluminum alloy material Product features: Bluetooth receive/transmit/U disk playback/TF card playback/digital to analog Battery capacity: 800mAh Input power: DC5V Transmission distance: 15m Power supply mode: Type-c Product size: 108.5 x 53.5 x 26.8mm