Digital CO2 Sensor PPM Meters Mini Carbon Dioxide Detector Gas AnalyzerOOTDTYChs:1. HCHO (formaldehyde) detection concentration range:0 - 1.999mg/m³;2. Range of concentration values detected by TVOC:0 - 9.999mg/m³;3. AQI air grade: 1 - 64. There is too standard an alarm prompt;5. Low voltage shutdown occurs;6. Lithium Battery Power (Built-in Non-Removable)Instructions:(1) Power on/off:Power on: press and hold the power button for 1 second, and at the same timeTurn on the phone after hearing a beep. Shut down: press and hold the power button for 5 seconds, then you will hear Power off after a beep. (2) Preheating: After power on, there will be on the LED screen every time200 seconds automatic countdown. This is a formaldehyde sensor control to measure the heating process. (3) calibration: After power on, put the detector outside the window for ventilationPlace for more than 10 minutes, then quickly press calibrationPress the 3 key, the instrument beeps (calibration successful),The data on the LED screen will return to: 0.000 calibration conduct. (4) detection: After the calibration is completed, place the detector in the measurement environment, the current value is the detected value, If the standard is not exceeded, the device does not beep. The standard values of formaldehyde and TVOC are:HCHO (formaldehyde): le standard; 0.10mg/m³TVOC: LE standard; 0.6mg/m³Specifications:Main color: whiteMaterial: ABSSscreen size: 2.8inDetect error: lt; 15%Battery: 3.7V, 1000mAhCharging Standard: 5V, 1ACstandby Time: About 240-360minTemperature: 18-50°CHightiness: 10-70%hrsMonitoring Varies: 20%-50%Product Size: 14x4x3.6cmPackage List:1 * Air Quality Tester1 * USB Cable1 * User Manual