A Neodymium-Iron-Boron permanent magnet which is substantially wider across a first axis than across the perpendicular second axis. The second axis is the axis defining the north and south poles of the magnet. At one of the poles is a permalloy cap which is substantially parallel to the first axis and inhibits the extension of magnetic flux from that pole and encourages instead a deep extension of the magnetic flux from the other pole. An aperture penetrates the magnet through the second axis which is wider at the pole away from the permalloy cap than it is at the pole adjacent to the permalloy cap. The shape of this aperture causes a distortion of the deeply extending magnetic flux lines at the pole away from the permalloy cap to be pinched inward toward the second axis rather than being parallel to it. The magnet thus provides a concentrated magnetic force that extends deeply out of its base so that the magnet can be placed on the exterior of a vessel or conduit with the result that the fluid inside is treated with optimized magnetic force.