Steering Wheel control Primary harness adapters convert the commands from your car's steering wheel controls to a code that an aftermarket radio can recognize. A patch lead is also requires for SWC type systems based on the brand of head unit you have. for more details check out our you tube video. http://aerpro.com/video/control_harness_installation CHMC4C Quadlock E-CLASS - (W211)2002 - 2009 SL-Class - (R230) 2002-2011
Hide Compatible with This product is also known to work in the following vehicles: Mercedes E-Class 2002-2009 W211 Mercedes SLK R171 2004-2011
