Holding magnets are magnet systems with an open magnetic circuit.The magnet is glued in a pot shaped body, while the active magnet faces down (in order to attach itself to the surface), concentrating the force of the magnet.
The magnetic field of the holding magnet is concentrated in order to achieve a better and stronger holding force than a regular magnet of the same size. The magnet is attached to a metal body, with the active (magnetic) surface facing downwards to attach to the desired surface. Holding magnets have a shallow magnetic field and are therefore typically not used over a gap.
Std Magnets NdFeBo