TVOC Sensor: The indoor air quality monitor design with TVOC sensor to monitor CO2 value, temperature and humidity of air quality to keep your in health environment, highly recommend to use it with USB charge Real-time Monitoring&Automatic Alarm: Carbon dioxide monitor can detect the air on real-time and when CO2 concentration 1999-above Four warning lights flashing at the same time to alarm Easy to Read: With intelligent color screen display and clear numbers.And when CO2 concentration 1600-1999 red warning light starts to flash and alarm Wide Application:Portable Co2 monitor with compact design suitable for monitoring the air quality at home, schools, office buildings, hospitals, restaurants, shopping malls, factories, hotels, laboratories etc Why You Need It: Perfet gift for your valentines day gifts for him/her/ kids, with the air quality monitor, you can definitely know what is your environment be like and improve it according to the actual situation