Through hole pot magnets are always measured as their diameter x depth. The size of the through hole pot magnet always includes the size of the shell within the measurements.
The diameter refers to the distance between the two widest points of the through hole pot magnet. The diameter ranges from 14mm (0.55″) to 100mm (3.9″).
The diameter you choose will depend on the role the through hole pot magnet is used for. If the through hole pot magnet is used as a retrieval magnet then the user will require a large diameter. This is because a large diameter through hole pot magnet will be able to secure the ferromagnetic material in a hard-to-reach place more securely than one with a small diameter.
The depth of a through hole pot magnet is the distance between the top of the shell and the magnetic face. It can range from 3.6mm (0.14″) to 22mm (0.87″).
The magnetic pull of through hole pot magnets ranges from 5.2kg (11.46lbs) to 164kg (361.56lbs).
The magnetic pull of a through hole pot magnet refers to the maximum weight of ferromagnetic material that the pot magnet can hold. It is determined by the materials the pot magnet is made from, rather than its overall size and depth. For more information, see page What are magnets made of?
To summarise, when purchasing a through hole pot magnet, the key thing to look out for is the diameter and the magnetic pull of the magnet. These are the two greatest variants of a through hole pot magnet and can affect the amount of ferromagnetic material it can hold securely. For example, a magnet with a large diameter and magnetic pull will allow the magnet to retrieve ferromagnetic materials from underwater.