These electromagnetic suspended globes are actually high-tech instruments. A magnetic field sensor permanently measures the height at which the globes are suspended. This sensor feeds that data into a micro computer in the base of the unit. This computer than calibrates the electronic magnets at the top of the frame based on the distance between the globes and the top magnet to keep the globes correctly positioned. All in the blink of an eye! So not only do these look great on your desktop levitating in thin air, they are also technology marvels! When you initially get your globe and plug it in, it may take you a few minutes to correctly position the globe in between the base and top magnets. You'll figure it out quickly enough and before you know it, you'll be able to set it up in just a few seconds every time. Once it's levitating, you can even spin it slightly and watch the globes rotate for extend periods of time. Just like the real thing, except you get to control gravity ;) This 4" model (8 inches tall including frame) features an attractive brushed metal silver frame and comes with a power supply.