Feature: 1. Multifunctional: This indoor air quality meter is multifunctional and can measure CO2 and PM2.5 levels. With a clear, easy to read display that shows CO2 levels from 400‑5000 ppm, PM2.5 levels from 0‑999ug/m³, time, temperature and humidity, this monitor ensures that you breathe health air. 2. Real Time Monitoring: This indoor air quality monitor samples 1.5s/time, and the alarm equipped CO2 monitor alerts you with a siren when the PPM value increases (supports turning off the alarm). You can calibrate the CO2 monitor to ensure its accuracy over time. 3. 2000mAh Large Capacity Battery: This air quality tester has a built in 2000mAh large capacity battery, you can use our CO2 monitor for a long time without replacing the battery frequently. Charging the CO2 monitor for 2 hours will ensure 24 hours of use. You can also adjust the brightness of the monitor to guard your eyes in different light. 4. Easy Installation: This PM2.5 CO2 temperature humidity detector is designed with wall mounting holes with wall hole stickers to aid in installation, easy to install, comes with a 10 foot USB charging cable so you can put it anywhere you want and charging it anywhere. 5. HD LCD Screen: This CO2 PM2.5 thermometer humidity monitor features a high‑definition LCD screen with a clear display, allowing you to clearly see the current room air data, which is very practical and convenient. Specification: Item Type: Air Quality Tester Screen Display: HD LCD Screen CO2 Detection Range: 400-5000 ppm PM2.5 Detection Range: 0-999ug/m³ Detection Temperature Range: -10°C-50°C Detection Humidity Range: 20%-85% RH Sampling Time: 1.5 Seconds Battery: 1 x 2000mAh Rechargeable Lithium Battery (Included). Package List: 1 x Air Quality Tester 1 x Manual 1 x USB Cable 2 x Screws 2 x Expansion Tubes 1 x Installation Sticker