| 摘要 |
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. |
