[5 in 1 Function]: The multi-function air quality monitor takes care of and can be widely used in home, office, classroom, hotel, gym, greenhouse, warehouse, etc. [Carbon Dioxide Tester]: Adopt semiconductor sensor, air convection detection, quickly and accurately detect CO2 concentration in living environment. [LCD Color Screen]: Displays CO2, CO2 index, HCHO (formaldehyde), TVOC, temperature, humidity and battery level. LCD color digital display for easy and clear reading even in dark environment. [4-color indicator and alarm buzzer]: 0-799PPM (Green), 800-1199PPM (Yellow), 1200-1599PPM (Orange), 1600PPM and more . The buzzer alarm when the CO2 concentration is higher than 1500PPM. [Rechargeable Design]: Built-in 1200mAh rechargeable lithium battery for strong endurance. With USB Type-C interface for fast charging via power adapter, power bank, laptop, etc.