Support battery-only use, get rid of the trouble of power cord restricting the usage location.Perpetual calendar setting: January 1, 2000 to December 31, 2099Time format 12HR/24HR display selectionWeek display in five languages: EN IT FR SP GE2 alarm clocks can be set, with a default 5-minute snooze function12 moon phasesIndoor temperature display range: 0+50 & +14+122, display resolution: 0.1 & Indoor humidity display range: 20%RH95%RH, display resolution: 1%RHOutdoor temperature display range: -20+70 & -4+158, display resolution: 0.1 & Outdoor humidity display range: 20%RH95%RH, display resolution: 1%RHTemperature display format selection (/)Level 3 comfort display for indoor environment433MHz ASK receiving OUTDOOR transmitter, maximum receiving 3 effective RF channelsOutdoor temperature upper and lower limit alarm and frost point alarm function.Temperature and humidity trend display Recording of maximum and minimum indoor and outdoor temperaturesAir atmospheric pressure display range: 850 hPa/mb1050 hPa/mb & 25.10 inHg31.01 inHg, display resolution: 1 hPa/mb &0.03 inHgAir atmospheric pressure unit selection: mb/hPa or inHgAir pressure change records in the past 1 to 12 hoursHistogram display of trend changes in barometric pressure over the past 1, 2, 3, 6 and 12 hoursFive-level weather forecast: sunny, cloudy, cloudy, rainy, rain+snow3-level pressure trend displayWhen using only battery, the screen data can be read normally without backlight. You can also use the button to light up the backlight for 5 secondsWhen using the power supply mode, the backlight is always on or the backlight is turned offpower supply: Host: 21.5V AA (battery not included in shipment) or USB power cable (included) Transmitter: 21.5V AA (battery not included in shipment)