1、[2 in 1 Bluetooth Adapter] In TX mode, the Bluetooth transmitter is plugged into non Bluetooth devices such as TV, PC and MP3 player via AUX RCA and transmits to Bluetooth headphones, speaker, soundbar; In RX mode, the Bluetooth receiver can be connected to wired speaker, earphones and to receive from smartphones via Bluetooth. 2、[Stable Connection and Stereo Sound] With latest Bluetooth chip and software, the Bluetooth adapter not only helps to upgrade your old devices to Bluetooth capable without replacing them but also a CD like auditory feast. Tap to pair with for NFC equipped phones to connect. 3、[Widely Compatible] Rich Interfaces: RCA, AUX. This Bluetooth 0 receiver transmitter can connect to any active speaker with a standard 5mm port or 2RCA port, which is very suitable for home theater, stereo and car speakers, as well as smart phones, and for Android devices. 4、[Work While Charging] Built in battery can support a full charge of the Bluetooth adapter at one time. Support 8h for receiving and 5h for transmitting. When in a low battery state, the adapter can be plugged into the power supply for charging while working. 5、[Support Auto Startup Shutdown] Use the charging cable to connect your car or other power sources. When the car starts or has electricity, it will auto turn on and auto connect to the device you connected last time. When the car is turned off, it will auto shut down. 1 x Bluetooth 5.0 Transmitter Receiver1 x 3.5mm Cable1 x Type C Charging Cable1 x RCA Cable1 x Manual  Item Type: Bluetooth  5.0 Transmitter ReceiverMaterial: ABSModel: BT-21Frequency Response Range: 10Hz-20kHzSignal To Noise Ratio: >90dBBluetooth Version: V 5.0Interface: RCA, AUXOutput Impedance: 75 ohmsDecoding IC: For Jerry ICEffective Open Distance: Approx.15m / 49ftPerformance: Stereo HiFi LevelBattery Capacity: 200mAh Li-ion Battery (included)Working Hours: RX 8h, TX 5h