A reusable magnetic device for the extraction of ferrous particles from a body of fluid, wherein the device comprises a plurality of magnets and soft ferrous metal spacers arranged in an alternating sequence to form a stack, adjacent magnets being arranged with like poles facing, a non-magnetic and non-ferrous end piece terminally disposed at a first end of the stack, and a non-magnetic housing that contains the magnets, the spacers and the end piece. The magnetic device can be installed in a vessel to provide a fluid filtering assembly.