CO2 Monitor 11in 4 in 1 Digital Sound Level Meter Thermometer Hygrometer Wall Mount Tester Item Type: CO2 Monitor CO2 Indicator: Green: 400~1000ppm Orange: 1001~2000ppm Red: 2001~5000ppm Decibel Indicator: One Green Light: <55db Two Green Lights: 55~65db One Orange Lamp: 65~75db Two Orange Lights: 75~85db One Red Light: 85~95db Two Red Lights: >95dB Function: Integrated decibel meter for the detection of CO2 concentration, temperature, humidity. Atmospheric Pressure: 86-106Kpa Sampling Time: 1.5 Seconds Decibel Measurement Range: 30~130dB Decibel Accuracy: ± 1.5dB Noise Detection Method: dB condenser microphone. Noise Concentration Unit: dB Frequency Range: 50Hz~8.5kHz Resolution: 0.1dB Detection Temperature: - 10℃ ~ +50℃ Temperature Accuracy: ± 1.0℃ (0℃ ~ 40℃) Temperature Unit: Celsius Storage Temperature: - 10℃ ~ 60℃ Detection Humidity: 20%~85% Working Environment and Storage Humidity: 10%~80% Humidity Accuracy: ± 5% CO2 Detection Method: Infrared NDIR. CO2 Concentration Unit: PPM CO2 Detection Range: 400-5000 ppm CO2 Alarm Value: 1000ppm Setting: Supports manual setting of 800ppm-2000ppm CO2 alarm threshold. Alarm: CO2 alarm on and off function. If you doesn't like the alarm, you can turn it off. Battery: 1 x 2000mAh, shipped with built in battery.