When the battery of your car is disconnected your radio is locked.With this application you can unlock your radio.Instructions:- Remove the radio or CD player from the dashboard.- The serial number can be found on a label located on the casing.- Enter the serial number and push the "Get Code" Button.- Enter the code to unlock your radio or CD player.Serial number must be starting with M. Compatible with: 3000, 4000, 4500, 5000, 6000,6006, 7000 and 9006.