Abstract: Elongate magnets are arranged about a copper fuel duct with each magnet having a like pole adjacent a flattened or faceted portion of the duct. Each magnet has a flat pole face and bevelled end edges with the bevelled end edges being in contact with the similar end edge of each adjacent magnet to define a tunnel through which the fuel duct runs. The duct is continuous through the magnet tunnel and terminates at each of its ends outside the tunnel in a peripheral bead or other attaching arrangement for coupling of the duct between a fuel source, such as a fuel pump, and a fuel consuming apparatus, such as a carburetor. The ducted fuel is thus exposed to flux lines of the magnets that are arranged about the fuel line to concentrate the lines of force at the fuel duct. The magnets and the fuel duct are held together by a surrounding capsule of non-magnetic material such as polypropylene plastic.