Consists of four metal rods of steel, brass, aluminium and copper embedded in a plastic holder. Each of the rods has a liquid crystal indicator to show the temperature up through the rod. The liquid crystal turns green at a temperature of 40°C, and this field moves up the rod as the heat is conducted. This demonstrates that some metals conduct heat better than others. Ready for a new experiment once it has cooled down. The rods can be used repeatedly, but only below 100oC.