Exo Terra Rept-O-Meter Hygrometer The Exo Terra Rept-O-Meter Hygrometer is extremely useful for checking the moisture levels and humidity in your reptiles terrarium. The Exo Terra Hygrometer is very easy to read and quick to install. It sticks on the walls of your terrarium and lasts throughout all sorts of climates. Simply set and forget it, which comes in handy for easy terrarium maintenance. Monitors moisture & humidity Easy to read & install Copes well in extreme climates