PROFESSIONAL BLUETOOTH HANDSFREE CAR KIT Production No.: H8122 --supports most of the bluetooth mobile phones --complies with the bluetooth 2.0 protocol and facilitates built-in bluetooth audio transmission --suitable for all the cars and trucks --suitable for 12-24 volt power application --support the voice dialing via the unit's microphone or of the phones --built-in DSP chip for background noise and echo cancelling --automatically mute the radio when an incoming call and outgoing call --built-in volume control to adjust volume --easy to change conversation mode between hansfree and private mode --supports to redial the last phone numbers --external speaker for option.