Bluetooth transmitter BC73
1. bluetooth V5.0 
2. Synchronize the mobile phone time, display the 24H time
3. BASS button
4. Directional  noise reduction MIC(Inhibition of electrical line noise)
5. AUX port: plug audio cable can enter audio output,  plug microphone can get call reception
6. Private answer 
7. Support power off memory function ,support bluetooth reconnect automatic
8. bluetooth support A2DP,AVRCP,HFP,HSP 
9. Support Siri/ Google voice assistant
10. Stereo
11. Double quick charge QC3.0,PD20W
12. Support input over-voltage protection, output over-current protection, output short-circuit protection and over temperature protection