You can insert this item into the back of the radio, then connect the red wire to 12V+ and the black wire to 12V-. Pair your phone or tablet with the module, select Aux on your radio, and play music through the speakers or make hands-free calls. It supports music playback from a USB stick or SD card. Condition: New Length: 150cm Compatible with Mercedes M-Class W163 COMAND APS 2.0 (19962001) Not compatible with head units that use fiber optic connections 1. Please confirm your car radio has an AUX input before purchasing. This product only works with radios that support AUX mode. 2. The version without a microphone does not support call answering. If call answering is required, a compatible microphone must be purchased separately. Color: As shown Material: ABS Package Contents: 1 x Adapter (Other items not included) Note: Due to lighting and display differences, the actual color may vary slightly from the image. Measurement tolerance: 13 cm.