Bluetooth Transmitter & Receiver - In TX mode, Bluetooth transmitter for headphones connects to non-Bluetooth devices (such as airplanes, gyms, TVs, or PCs) to enable Bluetooth functionality and transmit audio. In RX mode, the wireless audio transmitter and receiver connects to wired stereo systems (like car stereos or wired speakers) to add Bluetooth capability and receive audio Bluetooth 5.1 - Bluetooth 5.1 technology ensures more stable connection, lower latency, larger range, lower power consumption, faster transmission Long Playtime - It has a built-in 200mAh battery for longer working time Easy to Use - No need for any driver, no more setting, just plug and connect Universal Compatibility - Compatible with almost any Bluetooth-enabled devices, such as smartphone, PC, smart TV, Bluetooth headphones, Bluetooth speaker, Bluetooth receiver amplifier Specification: Bluetooth version: 5.1 Bluetooth connection range: 15m Product interface: 3.5mm audio interface Frequency response range: 10HZ-20HKZ Signal-to-noise ratio: less than 110dB Function: Bluetooth reception + transmission two-in-one Main functions: Bluetooth audio reception/transmission + call, 3.5 audio input, 3.5 audio output, toggle switch switch Size: 60*20*15mm