ISO HARNESS ADAPTER FITS Audi A3 BOSE Amplified System 2005 2012 Quadlock (Fakra) Audi A4 BOSE Amplified System 2005 2015 Quadlock (Fakra) Audi A6 BOSE Amplified System 2004 2011 Quadlock (Fakra) Audi TT BOSE Amplified System 2006 2014 Quadlock (Fakra)