Neodymium magnet, the strongest and most widely used magnets.
Super Strong NdFeB N35 N38 N42 N50 N52 Disc Small Mini Round Neodymium Magnet - China Small Mini Neodymium Magnet, Mini Neodymium Magnet | Made-in-China.com
Neodymium Magnets (NdFeB) | Arnold Magnetic Technologies
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