Surveillance: Audio / Video Devices

3.5mm single-channel Microphone. Can be clipped on car visor. Angle adjustable.

2.5mm single-channel Microphone. Can be clipped on car visor. Angle adjustable.

The device receives audio signal via Bluetooth and then converts & outputs to its USB / AUX interface for car / speakers etc.
The USB interface of your car or speakers should be able to play mp3 audio if you would like to use the bluetooth receiver's USB output.

For car playing MP3 files through USB drive. It requires that your car can play MP3 files and read USB file through AUX port.