For connecting a retrofit radio with an iso connection to a vehicle specific plug necessary for all opel models built since 1993 and with factory preequipment as well as for all vw and audi models especially audi a4 a6 and a8 built since 1993 and with factory preequipment depending on the special equipment of these vehicles the pin assignment on the radio connection is changed eg air conditioning automatic volume control moreover switched plus and continuous plus is changed this adapter allows