Neodymium Block Magnet 20 x 5 x 2 mm N35
 
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. N35 indicates the magnetic grade. The usual range is N35 to N52, with higher numbers generally indicating greater magnetic attraction. The rectangular block shape is practical for assembly. It is easy to align, provides a good contact surface and fits well into fixtures and grooves.
 
The 20×5×2 mm block is a good choice where a substantial but manageable hold is needed in workshops or light manufacturing. For good results, use a flat, clean metal surface. Any gap caused by thick paint or an uneven surface reduces holding force.
 
Warning: keep away from children. Strong attraction can cause pinching injuries, and the magnets may break. Store them with spacers. Keep them away from medical devices and objects sensitive to magnetic fields, including cards and electronics.