The Extech 445814 Humidity Alert Hygro-Thermometer has a programmable % RH audible and visual alarm that alerts you when humidity exceeds the set limit. A large LCD simultaneously displays temperature, humidity, and dew point. This product measures humidity from 10% RH to 99% RH ± 4% RH and temperature from -10°C to 60°C ± 1°C (14°F to 140°F ± 1.8°F). Rear calibration pot for humidity and temperature. Featuring maximum/minimum with reset functions that store and recall the highest and lowest readings recorded. Comes complete with built-in stand, wall bracket and one AAA battery.