you can just Insert this item to the back radio then Connect the red wire to 12V+, the black wire to 12V-. match your phone or pad to module.and Choose Aux from your radio, then you can use your phone to through speakers and talk to phone. it can work music on usb sticker or for SD card Condition: Length: 150cm for M-class W163 COMAND 2.0 1996-2001 not work on following headunit with fibre most 1. Please make sure your car radio has AUX mode before purchasing. This product is only suitable for radios in AUX mode! 2. The without a microphone does not have the function of answering calls, while the with a microphone has the function of answering calls. If you need the function of answering calls, you need to purchase a matching microphone. Colour:As Shown Material:ABS Package Contents: 1 x Adapter Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.