English: A "horseshoe" magnet made of Alnico, an alloy of iron, aluminum, nickel, and cobalt. Probably around 1 inch (3 cm) long. It is made in a "horseshoe" shape to bring the North and South poles of the magnet close together, creating a strong magnetic field between them. The metal plate between the poles at bottom is called a "keeper". It is left on the magnet when not in use, to prevent the magnet becoming demagnetized. By creating a closed magnetic circuit, it strengthens the magnetic flux in the magnet, making it harder for mechanical shocks or high temperatures to randomize the magnetic domains of the metal.