This is a Nicestuff 68305 (also known as the PR305 or NSD-68305 or 68305-PAC EasyMute Premium or KRAM 68305) handsfree integration harness for use withselect Audi vehicles with ISO radio connectors and premium audio systems with an external amplifier (ex: BOSE, JBL, Harmon-Kardon, Infinity, etc.). This kit features a soft-mute switching relay that sits on the line-level signal between the radio and the amplifier to provide a clean swithcing of the radio audio to the handsfree audio. Compatible vehicles include: 1998-2003 Aston Martin DB7 with Premium Audio 1992-1999 Aston Martin V8 Vantage with Premium Audio 1995-2005 Audi A4 with BOSE 1994-2004 Audi A6 with BOSE 1993-2003 Audi A8 with BOSE 2000-2006 Audi Allroad with BOSE 1994-2006 Audi Cabriolet with BOSE 1999-2006 Audi TT with BOSE 1999-2002 Range Rover with Harmon Kardon 1997-2004 Porsche 911 without PCM, with BOSE 1996-2004 Porsche 911 without PCM, with BOSE On activation of the Mute line, the audio will switchover to the handsfree kit. You can also use this harness to integrate audio into your car stereo from other mono sources by triggering the mute enable line (navigation units, radar detectors, CB radios, etc.). A carkit-specific adapter harness may be required for your installation (I have some of these in my booth), or the connections can be made individually. Available on the connection to the carkit is: VBATT - constant +12V power supply Ground - chassis ground Ignition - switched +12V signal Mute - active-low trigger Mute connection Speaker (+) - differential mono audio signal from the carkit or device Speaker (-) - differential mono audio signal from the carkit or device 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!