The steel shot and wax at the bottom of this glass thermometer allows it to float in solutions. This thermometer should not be used to stir the wort, nor should it be used to gauge the temperature of already boiling liquid. Temperature Range: 0-220 F (-10 To 95.5 C). Length: 9" (23Cm). This product uses alcohol, not Mercury, to measure temperature. It does not contain any toxic materials.