They are round magnets with hole in center and they can be also called: pot magnet with borehole, pot magnet with mounting holes, holding magnet with borehole, etc.
This is one of the most widely used pot magnets. They are made by gluing magnets and steel pots together. Filling materials are used upon request for a more powerful fix of magnet inside steel pot. With the use of either NdFeB magnet or ferrite magnet and steel pots in different diameters, these pot magnets come in variety of size & force combinations so that users can always find one that fits their application requirements. Generally, NdFeB pot magnets produce even higher holding force and are more expensive. Ferrite pot magnets are not as strong as NdFeB ones but they are less expensive.
The magnets with holes in the middle make it easy to fasten the pot magnet on, for example, walls, doors, wood boards, by using screw bolts
The wide adaptability of magnet with hole in center leaves users with enough space for their creativity in application.