Double Din Option: Allows for installation of aftermarket radios with big screens (up to 7").
Wiring Harness: Allows for installation of an aftermarket radio but some rewiring might be needed.
Canbus Interface: Allows for installation of an aftermarket provinding 12V ignition (that is not present in the vehicle) and navigation outputs)
Canbus Interface + SWC Retention: Allows for installation of an aftermarket radio while retaining use of the controls on the steering wheel that are lost when the factory radio is replaced. No programming required.
Antenna Adapter: Allows for installation of an aftermarket radio without the need to replace the factory antenna.
*Doesn’t make sense? Check this link for more info:
AUDI A4 (2002-2008) Build your radio installation combo