Key Features :
i : Clear viewing of the invisible lines of a magnetic field!ii : Steel filings are sealed in a scratch-resistant, transparent viewing tray.iii : Magnets are rubber coated to prevent scratching on the outside of the tray too.iv : Each kit includes 2 magnets (.75" disc magnet and 1" bar magnet) and filing-filled tray.v : Sold as a pack of 3 kits.