Neodymium Ring Magnet 20 x 5.5 x 3 mm N35
 
A neodymium (NdFeB) ring magnet is very strong. It is magnetised in a strong magnetic field during manufacture, providing high magnetic attraction in a compact size. Compared with ferrite, neodymium provides much greater magnetic attraction. The magnet generally has a protective surface coating. N35 indicates the magnetic grade, commonly ranging from N35 to N52; higher numbers generally indicate greater magnetic attraction. The ring magnet fits readily into a recess or around a hole and can be used on a shaft or screw, or as a spacer.
 
A good choice where stronger holding force is needed and a ring that fits over a shaft or screw is useful. (Ø20/Ø5.5×3 mm) Holding force depends strongly on the thickness and condition of the metal surface. It is greater on thick steel and weaker on thin sheet metal.
 
Warning: not suitable for children. Swallowed magnets can cause serious injuries. Seek urgent medical attention. Magnets can snap together suddenly, pinch skin and chip or break on impact. Separate them by sliding them apart. Keep them away from medical devices, cards and sensitive electronics.