The Extech 445814 Humidity Alert Hygro-Thermometer has a programmable %RH audible and visual alarm that alerts you when humidity exceeds the set limit. Large LCD simultaneously displays Temperature, Humidity and Dew Point. Product measures Humidity from 10 to 99% and Temperature from 14 to 140°F (-10 to 60°C). The meter has a basic accuracy of ±4%RH and ±1.8°F/1°C. Rear calibration pot for Humidity and Temperature. Featuring maximum/minimum with reset functions that store and recall the highest and lowest readings recorded.