Iron filing, 12 ounce, in a shaker for convenience plus screw cap for safe-keeping. They are ideal for experimentation with magnetic fields. When you place these filings on any magnet, you can visualize 3D magnetic fields. This demonstration is very common in the classroom and this is your chance to further study the magnetic properties at home. Warning: Because these shapes are small, they present a choking and poisoning hazard if swallowed. These small parts are not for children under 8 years of age.