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.

We had these nickel-plated spherical and hemispherical magnets made primarily to see, first of all, if it was possible and, second, to see if we could find uses for them. As with our other rare-earth magnets, we quickly found uses for them and expect to find more.

The hemispherical magnet (which makes a superb swivel anchor for a mobile) can be used in adjustable arms, specialized hinges, etc. The spherical magnet will hold a chain of ball bearings together to provide a near-frictionless rotating suspension mechanism. One can also be rolled along the crack in a hardwood floor, where it will stop and quiver like a Labrador on point whenever it rolls over a nail, so that you can map the nails and then cut into the floor without fear of tool damage.

The gee-whiz factor is very high for both magnets.

See this table to assist with fractional inches