Nickel Coated N42M Neodymium Magnet Disc is made from high performance Neodymium Iron Boron. The NORTH pole is on one circular face and the SOUTH pole is on the opposite face. These Magnets are plated with 3 layers of protective coatings - Nickel + Copper + Nickel (Ni-Cu-Ni). The maximum operating temperature of Nickel Coated N42M Neodymium Magnet Disc is up to 100 degrees C.