Neodymium Magnet in Steel Housing with Countersunk Hole 20 x 13,5 x 5 mm. 
 
A neodymium magnet (NdFeB) is very strong. It is magnetised in a strong magnetic field during manufacture, providing high magnetic attraction in a compact 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, commonly ranging from N35 to N52. Higher numbers generally indicate greater magnetic attraction. This magnet with a Mounting Hole for easy installation in a frame, holder or panel.
 
The 20×13,5×5 mm size provides a strong hold for practical tasks, including quick assemblies, attachments 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 during installation. Neodymium is hard but brittle and can chip or crack under excessive pressure. A washer can help.
 
Warning: keep out of reach of children. Magnets can snap together suddenly, pinch skin and chip or break on impact. Handle them carefully when bringing them together or separating them. Keep them away from bank cards, sensitive electronics and medical devices.