Long Distance TransmissionWireless Thermometer Hygrometer with 3 external sensors (frequency 433 MHz), you can place three sensors (IP54 waterproof) in different positions.Their data will be displayed on the same screen without frequent channel changes.The distance between the host and the sensor: the transmission distance is 300 feet / 91 m long (without obstacles and walls), and the effective transmission distance can reach 100 feet / 30 m (with obstacles).White Backlight & Smiling Face DisplayLCD screen shows clear arrows, you can see the temperature and humidity changes at any time.The backlight turns off automatically after 8 seconds without any adjustment.The smiley face symbol means -wet/comfortable/dry.Indoor temperature (0-50C / 32-122F)/outdoor temperature (-50C-70C / -58F-158F), humidity (20%-99%).Temperature and humidity accuracies are 1C/5%.Alarm Function and Calibration of Temperature and HumidityWhen the humidity and temperature reach the preset maximum or minimum, it will sound and the backlight color alarm (the backlight changes to red and'orange).If the temperature and humidity are outside the normal error range, you can manually correct the error by pressing the TIME-SET key.5 ButtonsOur hygrometer thermometer can record temperature and humidity over time, Min/Max button can display all maximum/small value data of temperature and humidity, long press can delete previous data andre-record.The C/F button can switch between Celsius and Fahrenheit.Additionally, there are alarm settings for time (12/24 hour format), date, and upper and lower limits for temperature and humidity.USB Power SupplyThe remote thermometer has two power supply methods, battery (not included) and USB cable power supply, easy to use, no need to worry about battery replacement (including USB cable).The thermometer can be attached through the hanging hole/pedestal.Very convenient to use.The three sensors have hanging holes on the back, which can be easily hung on the shelf.