Encased within a plastic shell magnetic marbles are an ideal introduction to the properties of magnets. These plastic cased marbles look like colourful plastic balls but each one contains a magnet so they stick together hang together and pull towards and away from each other - as a first introduction to the magical world of magnetism they are great fun.Excellent for teaching introductions to magnetism. Can be used with wand or horseshoe magnets. Pack of 20.WARNING! Not Suitable for Children under 3 years due to small parts.This product contains magnets or magnetic components.Magnets can cause serious or fatal injury if swallowed.