An assortment of Alnico magnets produced by The Arnold Engineering Co. in 1956. These are probably cast isotropic Alnico 5 magnets, and show the large range of shapes manufactured for use in devices such as loudspeakers, ammeters, and small DC electric motors. Invented during World War 2, Alnico 5 was at that time the most powerful magnet in the world. It's development created a new generation of compact permanent magnet motors and loudspeakers, devices which before the war had used DC electromagnets. Alterations to image: Cropped out surrounding ad copy.