Ferrit flat magnets with countersink are usually used to hang up objects. Simply attach the magnet to the wall with a screw and you have a smooth, strongly magnetic surface. The steel pot increases the magnetic holding force of the ferrite magnet. This achieves an adhesive force of up to 2.7 kg with a size of only 20 mm in diameter and a thickness of 6 mm.
Ferrite magnets can be used at temperatures of up to 200 degrees Celsius. They are also considerably cheaper than neodymium magnets. The holding force, on the other hand, is lower than that of neodymium flat magnets of the same size