Black Round Ferrite Permanent Disc Shape Magnet Cylinder https://www.mlmagnet.com/product/ferrite-disc-shape-magnet/black-round-ferrite-permanent-magnet-cylinder.html They are mainly used as power cores of linear motor actuators, vibrating engines; beacon backlights; voice coil motors; electromechanical meter movement,s etc. Login Login 0 repins 0 comments 0 likes