Features: It can accurately Monitors CO2, TVOC, HCHO, humidity temperature. You can Monitors the environment at any time. Equipped with a fast-responding and sensitive high-performances chip, the air quality Monitors can precisely capture the weak current generated during electrochemical reactions. 1200mAh rechargeable battery. Never be anxious about low power. Allows for better heat dissipation during operation, preventing the device from getting hot, and more accurate measurement data. Please notice that this air quality Monitors for indoor space, so please close the door & window before testing. Or else the data may not be accurate. We recommend using the Monitors and keep working for at least 60 minutes before reading the data. Specifications: Component:ABS Type:Black+Blue/White+Blue Size:Approx.70x35x90mm/2.75x1.37x3.54inch Note: 1.Please allow 1-2cm errors due to manual measurement, making sure that you not mind before order. 2.Due to the differences between different monitors, the picture may not reflect the actual of the item. Package includes: 1Pc Air Quality Monitors