For AUDI amplified subwoofer and rear active system!
 
For partially and fully active systems.
 
Active System Adapter
Audi
A2 / A3 / A4 / A6 / A8 1998>
Non Bose systems
 
Audi A2 1998 > 2004 Non Bose systems
Audi A3 1998 > 2004 Non Bose systems
Audi A4 1998 > 2004 Non Bose systems
Audi A6 1998 > 2004 Non Bose systems
Audi A8 1998 > 2004 Non Bose systems 
 
Allows for installation of an aftermarket car stereo in Audi models to connect the rear speaker system, there is no sound in the rear speakers without this adaptor.

For 1998 - 2004 Audi models (without quadlock connection)
 
 
Only for Audi with ISO Connection