The basic magnetic disc is the most universal in terms of use compared with the other magnetic discs. It is the best type to be used as the magnetic component in a range of different items such as machinery, or even the back of a pair of magnetic earrings.
To use a magnetic disc as a fridge magnet, the best variety to use would be a planning magnetic disc. This is because they can come in a large variety of different shapes and sizes which would make them an attractive and useful accessory on a fridge.
Countersunk magnetic discs are useful if using a magnetic disc on a non-ferromagnetic piece of material, for example a piece of wood. They are particularly useful for this task as they can be fixed onto the material with the aide of a screw, so would be a more permanent solution than a basic magnetic disc with an adhesive on one side.
Ring magnetic discs can be used when a magnetic disc needs to be inserted on to something, such as a fishing rod.
This is because the hole allows an equal thickness of material to be inserted through it, due to the hole having the same diameter through the entire depth, unlike a countersunk magnetic disc. The ring magnetic disc is particularly useful in speakers and computer memory.