Please allow the 0.1-0.2mm error due to the special nature of the magnet and the artificial measurement.
Neodymium (chemical symbol Nd) is element 60 on the periodic table. It is a rare earth metal and forms one of the Lanthanides series. When added to Iron (Fe) and Boron (B) (chemical formula Nd14Fe21B) the resultant magnets are the strongest magnets currently available. Neodymium magnets are sometimes known as Neo, Neod or NIB magnets.
Neodymium magnets are usually coated Nickel-Copper-Nickel plating to prevent the iron from rusting.
Usually placed in room temperature, the maximum operating temperature is 80 ° C , and it never will demagnetization.
Because the properties of NdFeB magnetic materials: hard, brittle, strong magnetic field, to handle with care (especially for large size and thin)