Handsfree Rearview Mirror. Caller ID shows on LED Display, Voice dialing, last number re0dialing and stores up to 200 entries in the phone book,Noise supression & echo cancellation technology, Built in microphone and dual stereo loudspeaker, Broadcasts to your vehicle's FM radio turning your car radio into your phone or MP3 music player speaker. Plays audio from your MP3 player or any other audio device with a audio output jack, Easy installation: the mirror simply clips over the to of your existing mirror rechargeble battery with 12 VDC power supplied from your car's DC socket. Runs about a week between charges.