CMS Magnetics N42 3" x 1.65" x 1/2" Ring, Package of 1 Permanent Neodymium Magnets Super strong neodymium rare earth magnets, patent licensed products Grade - N42 stronger than Grades N40 and N35 Can hold up to 116 lb each magnet Magnetized through 0.5", poles are on the two flat surfaces Can be used for Holding, motors, generator and science projects.