Remember playing with iron filings and a magnet” The magnet makes the filings stand up on end and arrange themselves in beautiful patterns according to the magnetic field lines. The problem was that the filings would stick to the magnet so hard it was difficult to remove them AND filings that spilled made a huge (and rusty) mess. This clever device solves both problems by enclosing the iron filings in a clear hard plastic case! Now students, children and adults too can enjoy learning about magnetic attraction the fun and clean way. You must supply your own magnet, but just about any magnet will do. And when you are done, just put it away in a drawer and there’s nothing to clean up. 3″ round.