RING HAS PERMANENT MAGNET

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The ring is made from a series of permanent rare-earth magnets, e.g. of neodymium-iron-boron, samarium-cobalt or similar, having a circular cross section, each in the shape of a cylinder, sphere, plane surface or disc. The lateral magnetic surfaces enable them to hold together in a ring of the required size; they are plated and have a coating of siliceous material.