Neodymium magnets are available in many different grades but most commonplace are N42 and N52 grade magnets. Standard Neodymium magnets have a max operating temperature of 80°C and are available in different strengths.  These magnets are prefixed with the letter ‘N’ followed by a number, the higher the number the stronger the magnet.  N35 is the starting point and increases through to N52 as standard.  The number relates to the Maximum Energy Product of the magnet. Neodymium can also be manufactured to operate at higher working temperatures and these magnets are identified with a different letter or letters at the end of the code: M = 100°C H = 120°C SH = 150°C UH = 180°C EH = 200°C AH = 230°C