Very good84/100
Small meter with memory function. Many display options, but an unlit display. In twilight, this is no longer of much use. The traffic light can only be read well directly from the front.
More than 1.000.000 measured values can be saved as a CSV file on a Micro SD card for later analysis on a computer.
The three-colour display indicates the current air quality from green through yellow to red, enabling a quick visual assessment of the CO2 level.
The recorded temperature range of 0-50 °C covers typical indoor environments.