Nickel Coated N42 Neodymium Magnet Arc is made from high performance Neodymium Iron Boron. The maximum operating temperature is up to 80 degrees. 37.5 O.R x 33.5 I.R x 25 wide x 4mm thick N42 Neodymium Arc Magnet (South). The NORTH pole is on the outer radius and the SOUTH is on the inner radius. These Magnets are plated with 3 layers of protective coatings - Nickel + Copper + Nickel (Ni-Cu-Ni).