The wall-mounted DuoControl change-over controller system for the two-cylinder system with integrated gas pressure regulator and test connection (for vehicles from 2007 onwards) can only be used if no heating is required while the vehicle is in motion. The gas cylinders must be closed during the journey. Cannot be used for commercial vehicles. May not be used in closed rooms (e.g. household) or in mobile homes in Germany. Installation only by an authorised specialist. Note: Can be used without restriction for end-of-life vehicles ( before 2007 ). Also suitable for operation with a gas cylinder.