An electrical device (1) which exhibits PTC behavior and which comprises a resistive element (7) electrically connected to first and second electrodes (3, 5). The resistive element is prepared from a composition comprising a curable polymeric component (9), a first particulate filler (13) which is both electrically conductive and magnetic, and an optional second particulate filler (15). The first particulate filler is dispersed in the polymeric component in discrete regions (11) which extend from the first electrode to the second electrode. Devices of the invention can be used as circuit protection devices or heaters. Also disclosed is a method of making an electrical component in which a composition comprising an electrically conductive and magnetic particulate filler is positioned on a layer which comprises a magnetic pattern to form an element, and is then cured so that discrete regions of the particulate filler form corresponding to the pattern.