Magnetic field viewer card shows the magnetization pattern of permanent magnets. Two magnets may look identical but have different magnetization patterns. Place the field viewer directly on permanent magnet to see the multiple Pole, 2-Pole, or conventional magnetization pattern. Also, views magnetization patterns and size of a permanent magnet encased in layer of aluminum or stainless steel.
Magnet Source Magnetic Field Viewer Card (Pack of 1) - B005HYCM8M