Function: Measure indoor and outdoor temperature and humidity, Celsius and Fahrenheit conversion Maximum and minimum temperature and humidity memory function Can view historical temperature and humidity data Up to 3 outdoor units can be connected (one outdoor unit is included in the regular package) There are two high magnetic magnets on the back shell of the host, which can be adsorbed on metal objects There is a stand on the back of the main unit, which can stand in a horizontal position High sensitivity touch button control, easy to operate Comfort indicator, temperature and humidity trend indicator HTN large-screen high-definition angle-free color screen LCD display With backlight, automatically turn off the backlight after 10 seconds without operation The outdoor unit can be hung using the hanging holes, or it can stand on a horizontal surface Outdoor unit XP4 waterproof parameter: Indoor Temperature Range: -4F - 158F (-20C - 70C) Outdoor Temperature Range: -40F - 158F (-40C-70C) Humidity range: 20%-95% Comfort Display: Dry, Comfort, Wet Temperature display unit: C/F optional (default is C) Temperature Resolution: 0.1C/F Humidity Resolution: 1% Refresh rate: 10 seconds. Error: temperature plus or minus 1C, humidity plus or minus 5% Wireless receiving range: 60 meters/197 feet RF wireless frequency: 433 MHz Power supply: No. 7 battery (regular delivery does not include batteries)