Automotive Parts Accessories Professional Customized Neodymium Magnet N55 N54 N52 N50 N42 N40. Neodymium magnets are graded according to their material. In general, the higher the score (the number after N),the stronger the magnet. The highest grade of neodymium magnet currently available is N52. Any letter following the grade refers to the temperature rating of the magnet. For more details, please contact us for a quote, thank you！