Sintered neodymium magnets has complex manufacturing process and the properties is very good comparing to the price. It is strongest magnetic material since now and is widely used in motor, high energy louderspeakers, MRI,wind generator,etc.

As sintered neodymium magnet can not work at  very high temperature and is easy to be rust, it is always coated with nickel plating, epoxy,Zinc. New coating is also available like everlube, parylene,etc.