BRAND NEW Jupiter Jack is an easy to use device that turns your car radio into a hands fee speaker phone. It is easy to use. Simply plug Jupiter Jack into your cell phone's headset jack and tune your car radio to 99.3 FM and start talking hands free. It's that simple. Jupiter Jack features a built in microphone that transmits your voice clearly while you hear your caller's voice clearly through your car's speakers. Using a cell phone without a hands free device is dangerous and is illegal in many states. Now you will enjoy clear robust sound that only your car speaker can provide allowing you to conveniently talk and drive at the same time. Jupiter Jack works with any cell phone with a headphone jack. Some phones may require an adapter, of which the most common are included in the package. Battery included.