SoundTek A1+ This is a high end excellent sound Aux Bluetooth car-kits receiver for all cars which have 3.5mm Aux In port or for home audio system, Support Multi-point/Dual link Excellent Sound Best Audio Quality, Aston Innovatons's noise free technology 100% kill the hum/buzz/static/hiss noise, No need an extra ground loop noise isolator any more Audio Technical Spec Signal to noise ratio:>95dB | THD+N:<0.04% @ 20-20K Hz | Frequency response:+/-0.5dB @ 20-20K Hz | Output level:1Vrms (sams as iPhone) | Channel balance:<0.1dB | Crosstalk: >80dB Advanced Audio Decoder Support AAC SBC audio decoder - better than CD quality Crystal Handsfree Calls Build-In high performance microphone, CVC noise reduction, Full-duplex HD voice processing, AGC algorithms, Excellent Handsfree Call Quality Auto On SoundTek A1+ will auto on when you start the car, then auto link with the last connected phone (phone Bluetooth need on) Smart Backlit Buttons All buttons have backlight LEDs, Which is much more easy and safe to use even at night Voice Assistant Support voice assistant such as Siri, Google Now ,Cortana (Just press and hold the play button about 2 seconds to active voice assistant) Travel and Talk Use the SoundTek A1+ to make your car Bluetooth compatible, a complete handsfree solution. Play music from your phone, make and receive calls and more! Simple Operation Three buttons take care of all possible functions. Play and pause music, answer and hang-up the phone, skip forwards or backwards, Vol+ or Vol- To get the Best Audio Quality, Please adjust the volume of Receiver and Phone to Max in Music,Phone,Voice assistant mode first, Then adjust car stereo volume to right level