Extech RH35 Radar Desktop Hygro-Thermometer Alert measures Humidity, Temperature, and Dew Point of the former 24 hour period with Facial icons to help indicate dry or humid conditions. A happy face is displayed when RH is between 40%RH and 60%RH, a Frowning face is displayed when the RH is below 40%RH (too dry) and above 60%RH (too humid). The Extech RH35 features a full-sized display, audible and LED alerts, and MIN/MAX features.