Accurate Sling Psychrometer - 5 ~ 50 Celsius. Obtain fast and accurate humidity readings anywhere by comparing the reading of the wet and dry bulb thermometers on the enclosed humidity chart. Eliminates the hazard of splattering mercury by using a safe and easy to read red liquid. The thermometers are recessed into a protective plastic mounting. The mounting also contains a water reservoir eliminating the need to constantly rewet the wick. Comes with a carrying case and plastic humidity chart.