The Exo Terra Analog Hygrometer allows you to monitor the humidity level in your terrarium. Correct humidity levels are essential for the overall health of reptiles and amphibians. Incorrect humidity levels may lead to electrolyte imbalance, dehydration, improper shedding, hyperkeratosis, respitory infections etc. Humidity requirements vary greatly depending on the species and their natural environmental conditions. Carefully research the specific humidity needs of your species.