The Aerpro CHMC6C Steering Wheel Control Interface (SWC) allows you to upgrade to an aftermarket headunit whilst maintaining use of your factory steering wheel controls. Engineered to suit various Mercedes vehicles with Audio 10, Audio 30 or APS original stereo and with 10 Way ISO connector, the steering wheel control interface includes a harness that is fitted with a vehicle specific plug designed to connect directly into the existing wiring in the vehicle with ease, no cutting of the factory wiring harness in the vehicle is required. Installation of the aftermarket headunit is simplified even further when paired with the optional Aerpro APP9 Headunit Secondary ISO Harness & SWC Patch Lead, which connects between the aftermarket headunit and the Aerpro Steering Wheel Control Interface. This interface is CANBUS compatible and provides various outputs including Reverse Trigger, Park Brake, Speed Pulse and Illumination. * Please Note: - Steering Wheel Control Interfaces vary between models, to find the correct part for your vehicle use the Aerpro Vehicle Selector. - A Steering Wheel Control Patch Lead is required to be used in conjunction with this part to enable Steering Wheel Controls to function (sold separately). - Aftermarket headunit must be SWC compatible and Steering Wheel Control Functions may vary from the OEM Functions. - Suitable for vehicles with Audio 10, Audio 30 or APS original stereo and with 10 Way ISO connector. - Due to the audio options fitted from factory we recommend removing the factory unit to confirm the compatibility if the harness prior to purchase. There are two harness options to suit Mercedes C-Class W203 (2000-2004) that have ISO 10PIN Factory headunit plugs. The CHMC6C suits cars with BROWN CANBUS WIRES, whereas the CHMERC suits cars with BLACK CANBUS WIRES.