ISO adapter harness for fitting a new stereo in an Audi A2, A3, A4, A6 or TT with an original BOSE amplified audio system with ISO connectors are the back of the head This harness adapts from the original ISO and Mini ISO connectors at the back of the head unit to standard aftermarket ISO connectors. The harness has a built in high to low level audio adapter to drop the speaker outputs from the new head unit to a low line level signal to work with the original amplifier in the car. The high to low level adapter has 4 dials to individually set the levels of each audio channel to give perfect sound quality. The built in CANbus interface generates an ignition supply, this means installation is plug and play. PLEASE NOTE: Some early Audi TT cars will have CANbus wires at the back of the radio but do not carry the CANbus ignition data. Compatibility List Audi - A2 (2000 - 2005) Audi - A3 (8L) (1996 - 1999) Audi - A3 (8P) (2003 - 2007) Audi - A4 (B5) (1995 - 2001) Audi - A4 (B6) (2001 - 2005) Audi - A4 (B7) (2005 - 2008) 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.