The seat occupancy mat is a sensor mounted in the front passenger seat. The emulator simulates a situation of a person sitting in the passenger seat with a seat belt fastened. To make the emulator work you need a diagnostic tool (like for , for etc.) to remove old errors of a broken seat mat that are stored in the control unit. Once you connect the emulator your diagnostic tool be to remove old errors and turn off the SRS/warning. Unfortunately, the errors related to the safety systems are not removing automatically. Before purchase, please scan your car with a diagnostic tool to make sure your SRS/ warning is caused by a defective seat mat. Fitment Type:Direct Replacement Install Fitment:Suitable for CLK W203 W208 W209 V250 2006-2012 Due to different product batches, the appearance , which does not affect the use. Colour:As Shown Material:Plastic Package Contents: 1 x Car Seat Bypass Emulator Sensor 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.