Indoor CO2 Monitor: Compact size Body with hollow back design for carring and airflow. Big colorful LCD digital screen for people easy to identify and read. Not only monitoring the CO2 content, also can test the temperature & humidity. Air quality monitor is Keeper of family health, Perfect for home interior, such as living room, baby room, classroom, office and which closed places etc. Necessity of Air Quality Monitor: Carbon dioxide (CO2) is not harmful to human body when it is low, but when it overs a certain amount, it will affect the breathing of humans (and other organisms). If serious, life is threatening. Thus, we have to monitor the CO2 content of air for keeping health. Advanced NDIR Technology: Mini CO2 meter uses high precision NDIR sensor technology to detect carbon dioxide content accurately and quickly. and it can hazard assessment, when CO2 of air exceed the setting alarm value(alarm value: 1000 PPM), it will warn to remind people to open the window or turn on air purifier for keeping balance of air. Air Semiconductor Sensor: 4-in-1 air quality monitor adpots intelligent air semiconductor sensor to test the temperature and humidity value of air. Compare with the common sensor, it is more sensitive, accurately and stable. Convenient for Carrying: CO2 Monitor built-in 1600mAh battery. It can be used continuously for about 8 hours after full charging.So don't worry, take the CO2 meter to anywhere you want go.