[Face Alarm]: The face of the CO2 Monitor is automatically switch when the CO2 at different level. [Green Face]400~1000ppm;[Yellow Face]1001~2000ppm;[Red Face]2001~5000ppm [Buzzer Alarm]: CO2 Detector is to emit buzzer alarm when the CO2 level exceed the setting threshold(defalut is 1000ppm), you may manually set the alarm threshold by double click the power button [High Precision]The CO2 Meter is equipped with NDIR sensor, assure the accuracy measurement, it can measure carbon dioxide(400~5000ppm), temperature and humidity [LCD Screen ]Carbon Dioxide Detector is designed with colored and Large screen, very clear to monitor the air quality, help to keep the indoor air healthy [User-Friendly Design]The CO2 Monitor comes with Multi-Functions, Calibration, Bulit-in battery, USB cable and is compatible with any standard 5V DC power source Please note: the physical slightly color difference or difference, does not affect the use, please do not mind, thank you! Material: plastic colour: As shown Package Contents: 1 x CO2 detector 1 x data cable Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.