If you are retrofitting the UHI system to a W168 A, W202/W203 C, W208/W209 CLK, W210 E, R230 SL (pre 05) W220 S (pre 2004), W215 CL (pre 2004) with the CD based COMAND, or Audio-10, or Audio-30, or Audio-30-APS sytems AND already with a Mercedes phone system in it then this adapter will convert the existing antenna wiring (mini UHF connector) to the UHI type (purple fakra) connection thus allowing the use of the car's external antenna rather than the stick on antenna supplied with the retrofit kit.