The Exo Terra Hygrometer monitors humidity levels effectively and easily. The humidity level is an important factor in keeping your reptiles or amphibians healthy and stress free. It is easy to read and install. Maintaining the proper temperature and humidity levels in a terrarium is vital for the well-being and health of all reptiles and amphibians. Exo Terra has developed a complete line of terrarium accessories, including the Exo Terra Hygrometer that will help you monitor and maintain proper temperature and humidity levels for tropical, rainforest and desert environment.