Until you have actually used rare-earth magnets, you cannot appreciate their strength. The strength of these magnets has to do with the electron array in the neodymium, the rare earth they are made from. This force only increases with the magnet’s dimensional size.
Ring magnets stack wonderfully on a rod or a taut cord if you place them with similar poles facing. You can design an awe-inspiring horizontal top by putting two ring magnets on a rod and hiding four magnets in the horizontal base.
There are hundreds of uses for these magnets. Nickel plated with slightly rounded edges, they can be glued in place with almost any glue (epoxy is the most secure).
Dimensions given are outside diameter by thickness, with inside diameter in brackets.