Magnet mainly classified as permanent magnet and soft magnet. And permanent magnets are classified as metal alloy magnets(including Neodymium-Iron-Boron magnets, Samarium-Cobalt magnets, AlNiCo magnets ) and hard ferrite magnets.
Ferrite magnets is sintered permanent magnets. Compared with other permanent magnets, ferrite magnet is hard and fragile, its magnetic energy is low. But is is not easy to be demagnetized and corroded, its production engineering is easy and price cheaper, and widely used in industry production.
Magnets have no radiation to body, only laser and cesium heavy metal can produce radiation to body.
The earth itself have super magnetic field, so body has adaptability to magnetic field even if dependence on magnetic field. Medical domain speaking weak and stable magnetic field is good for health, so kinds of magnet therapy items produced.