This is a Peripheral PXVWHF1 VW CelFi Plug-n-Play Phone Harness. Use this harness with a bluetooth handsfree kit like the Motorola IHF1000 so that the factory VW radio will automatically mute and route the phone audio through the stereo when making or receiving a call. Make sure that your vehicle/radio is compatible before ordering. I have also modified these harnesses to integrate a handsfree systems into Porsche 911 / Carrera, Cayman, Boxster and Cayenne vehicles with PCM2.1 radios, as well. I have a mobile electronics installation business, and am selling off some excess inventory. Please feel free to send a message if you have further questions about any of my items. Thanks for looking!