Neodymium Magnet in Steel Housing with Countersunk Hole 40 x 13,5 x 5 mm. 
 
Neodymium (NdFeB) is among the strongest magnetic materials and provides substantial holding force for its size. It is much stronger than conventional ferrite magnets and generally has a protective coating because the material can corrode over time. The N indicates the magnetic grade. NdFeB grades commonly range from N35 to N52, with higher numbers generally indicating stronger magnets. The with Hole design for mechanical attachment, allowing screw mounting without adhesive.
 
The The 40 x 13,5 x 5 mm size provides a strong hold for practical tasks, including quick assembly, attachment and technical projects. 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: keep away from children. Strong attraction can cause pinching injuries, and the magnets may break. Store them with spacers. Keep them away from bank cards, sensitive electronics and medical devices.