This can be used for showing magnetic field patterns either on the bench or on a overhead projector. Comprising a shallow transparent chamber, 250 x 180 x 7mm overall, containing iron particles suspended in a liquid. It may be used to show fields in much the same way as with loose iron filings on card but with much greater convenience.The transparent construction allows for demonstration use on a over head projector, or the device may be placed over a piece of white paper to provide background. Supplied with two pairs of bar magnets and an instruction/experiment booklet.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.