An electrical item (the working element of which is constructed essentially of metallic substances) which changes alternating current to direct current by the rectifying action occurring at the junction interface between a metallic conductor and a semiconductor. Excludes sets of metallic rectifiers which are not rated for rectifying capabilities but are used as suppressors. For items containing germanium or silicon, see semiconductor device (1), diode; semiconductor device set and rectifier, semiconductor device. For a complete power supply utilizing metallic rectifiers, see power supply.