This is a special pot magnet assembly, it is not like other pot magnets with mounting holes and no threaded holes, made of metal shell + strong neodymium round magnets, the black color you see are made of black epoxy coating, this magnet is magnetic on one side only, suction up to 20kg or more, the maximum temperature of use shall not be higher than 75 degrees Celsius, can be customized to a higher temperature resistance, support for separate packaging.
Other common pot powerful magnets;