1. USB Power Supply, Built-In 500MA Battery, Always Uninterrupted, And Can Be Used After Power Failure; 2.9-Inch Lcd Screen Display, Clear Visibility; 2. Five Major Displays (Temperature, Humidity, Brightness, Time, Date); App Monitors The Whole Process All The Time, Sets Upper Limit And Lower Limit Alarm; Effectively Overcomes The Traditional Disadvantage Of Not Being To Control All The Time; 3. Smart Off/On Backlight/Dot-Saving Mode; Precise Detection, Real-Time Detection, One Measurement Per Second; 4. Support The Temperature Unit To Switch Freely (-), Completely Solve The Different Units In Different Countries; 5. Easy To Install, Fixed And Placed On The Desktop At Will;Wifi Temperature/Humidity Detector, Large LCD Display;Support The Mobile APP To Set The Upper Limit And Lower Limit At Will. When The Lower Limit Is Set, The Device Starts To Send An Alarm And The Mobile App Receives The Alarm Information; Working Voltage: DC 5V Quiescent Current: 30mA Humidity Measurement Range: 0-100%Rh Temperature Measurement Range: -19C - 60C ( 28.5F - 42.8F ) Temperature Measurement Accuracy: 0.3C Humidity Measurement Accuracy: 2% Brightness Measurement Range: 0-100% Charging Time: less than equal 2 Hours Battery Life: less than equal 4 Hours (Full Charge State) Built-In Battery Specification: 3.7V / 500mAh (Used In Power Failure/Power Off State) Wifi Standard: IEEE 802.11 B/G 2.4GHz (Does Not Support 5G) Due to different batches, there may be differences in product appearance and printed text, which will not affect use Colour:White Material:ABS Package Contents: 2 x Temperature Humidity Sensor Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.