Car USB Interface Aux-in Adapter for Mercedes Benz W203 C Audio AC289 Good product with high quality material. Mercedes AUX lead connects via Mercedes Quadlock connector at rear of compatible radios. Please verify that your Mercedes radio has the Quadlock connector and CD/Aux button before ordering. Feeds the audio from devices such as iPod, iPhones, iPads, MP3 players and mobile phones into your Mercedes head-unit as an auxiliary input. Gold plated connections for superior sound quality. Provides a far superior sound quality compared to cheap FM modulators.