ISO adapter harness for Audi cars with ISO and mini ISO connectors at the rear of the head unit. The harness has a built in adapter to drop the rear speaker outputs from the new head unit to a low line level signal to work with the original amplifier in the car. Some cars may have an ignition supply in the original harness, other cars may not and an ignition supply will need to be connected.Compatibility List Audi - A2 (2000 - 2005) Audi - A3 (8L) (1996 - 1999) Audi - A3 (8L) facelift (2000-2003) Audi - A3 (8P) (2003 - 2007) Audi - A4 (B5) (1995 - 2001) Audi - A4 (B6) (2001 - 2005) Audi - A6 (C5) (1997 - 2004) Audi - TT (8N) (1998 - 2006) Vehicle Models: The years stated refer to the model's years of manufacture, please check the item description for information about any changes there may be within these productions years.