Ring joint gaskets are classified as two basic types, an oval cross section, and an octagonal cross section. These basic shapes are used in pressures up to 10,000 psi. The dimensions are standardized and require specially grooved flanges. The octagonal cross section has a higher sealing efficiency than the oval. The sealing surfaces on the ring joint grooves are smoothly finished to 63 micro inches and are free of objectionable ridges. The hardness of the ring is always less than the hardness of the flanges.
Ring magnets can be magnetized in different ways. It attracts the small neodymium magnet with just the right amount of force to counteract gravity. They all are magnetized such that the north and south poles are on the flat surfaces. Each can be used to build a simple loudspeaker. The two smaller ones are N42 grade rare earth magnets and are nickel coated. The larger is a ferrite ring magnet which is epoxy coated. The magnet floats, being repelled by the top and bottom bismuth disks. They are used to retrieve metallic objects by tieing a string around them. It has strong force.