Demonstration kit comprising a 5 litre round bottom glass flask complete with a cork ring stand 450g of plastic modelling clay and one each of the following 50mm diameter meniscus lenses:+11D+8D+5.5D+2.5D-3DThe first three lenses are fixed to the flask with plastic modelling clay to show short normal and long sight respectively when a beam of light is passed through them. The other two lenses are used for correcting the long and short sighted condition. The flask is filled with water and a little fluorescein is added (B8A67919 - sold separately) in order to show the path of light through the model eye.Ideal for use with the LED.white (B8L87348) or a laser.Fluorescein Sodium Salt is available separately - B8A67919: 5g.