Neodymium Block Magnet with Countersunk Hole 40 x 10 x 5 mm N48. 
 
Neodymium (NdFeB) is among the strongest magnetic materials and provides substantial holding force for its size. Its magnetic attraction is greater than that of ferrite magnets, and the surface coating helps reduce corrosion. N48 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 40×10×5 mm block is suitable where a substantial but manageable hold is needed in workshops. For good results, use a flat, clean metal surface. Any gap caused by thick paint or an uneven surface reduces holding force. Use moderate tightening force, avoid overtightening and use a washer where possible. Impacts or excessive clamping pressure can crack the magnet.
 
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 medical devices and objects sensitive to magnetic fields, including cards and electronics.