Rubber coated pot magnet with threaded stem

These magnets have a screw thread and are covered with a layer of rubber. The rubber protects sensitive surfaces from scratches and increases friction so that the magnet does not slide off a smooth surface. As there is a hole in the rubber at the threaded rod, these magnets are not recommended for outdoor use as they can rust. Pot magnets with threaded rod are also available without rubber. See link below.