Wagan Handsfree Rearview Mirror provides a safe way to communicate while driving. A caller ID shows on the LED on your rearview mirror and it broadcasts the FM radio, turning your car radio, into your phone or MP3 music player speaker. Install the mirror by clipping it over the top of your existing mirror. Technology offers voice dialing, last number re-dialing, and stores up to 200 entries in phone book. Recharge battery with 12 volt DC power is supplied from your car’s DC socket that runs about a week between charges.