Neodymium Magnet in Steel Housing with Countersunk Hole 120 x 13 x 5 mm. 
 
An NdFeB (neodymium) magnet provides high magnetic attraction for its size, making it useful for technical projects and practical attachments. Compared with ferrite, neodymium provides much greater magnetic attraction. A protective surface coating helps improve durability. The N indicates the magnetic grade, commonly ranging from N35 to N52. Higher numbers generally indicate greater magnetic attraction. The with Hole design allows stable, repeatable screw mounting.
 
The larger size suits demanding tasks such as strong attachments, assembly and robust projects, with careful handling. Holding force depends strongly on the thickness and condition of the metal surface. It is greater on thick steel than on thin sheet metal. Do not overtighten the screw when securing the magnet. Neodymium can break under impact or pressure. Use a washer or spacer if necessary.
 
Warning: not suitable for children. Two magnets can snap together quickly, pinch fingers and crack or chip. Separate them carefully and avoid impacts. Keep them away from medical devices and objects sensitive to magnetic fields, including cards and electronics.