Neodymium magnets are offered in several different grades. The first section N30-45 has an operating temperature of up to 80 degrees. Most of our stock only goes up to N38. The second section, denoted with the "M" prefix after the grade has an operating temperature 100 degrees. After this the grades are "H", "SH", "UH" & "EH". In order for the magnet to withstand a higher operating temperature, during production more of the raw material PrNd is incorporated as these elements have a naturally occurring resistance to high temperatures.