Abstract: A housing has a magnetic block therein with (preferably) an exposed side. The housing has (preferably) an integral, annular, curved, elastomer skirt forming a suction cup. The suction cup is used to attach the magnetic block to the external side of an oil passageway, e.g. an engine oil filter cartridge, such that the exposed side abuts, or nearly abuts, the passageway, the exposed side being a centralized base of the suction cup. The magnetic lines of force emanating from the magnet penetrate beyond the wall and attract magnetically attractable particles from oil passing thereby. The particles are held against the side opposite the magnet.