Fuel systems for internal combustion engines; Fuel economisers for motors and engines; Fuel feed apparatus for engines; Insulated metal pipelines (parts of machines, engines or motors); Insulated metal pipes (parts of machines, engines or motors); Insulated metal tubing (parts of machines, engines or motors); Liquid filtering apparatus (parts of engines or machines); Catalytic converter units for vehicle exhausts; Catalytic converters; Emission control apparatus (catalytic converters) for exhausts