Ring magnets are any magnets that have a central hole. They can be regular magnets with a plain hole or countersunk, counter-bored or threaded.
Basic ring magnets without any additional machining can be magnetised with their north and south pole on opposite circular faces or diametrically magnetised so that the north pole is on one curved side and the south pole is on opposite curved side. They are used in many everyday appliances such as vacuum cleaners plus motors, generators, rotor shafts and more.
Regular countersunk magnets are available with either pole on the countersunk face while pot magnets with a countersunk, counterbore or threaded hole are magnetised on one side only.