This is a Japanese-made CO2 concentration meter. It's very easy to understand because it uses colors to indicate the level, and it reacts quickly to things like human breath. I used it temporarily in a new building, but I'm selling it now that I'm finished with it. It's in good condition. Only the main unit and cable are included. The instruction manual is not included, but it can be viewed on the manufacturer's website. Operation has been confirmed. With the CO2 Lamp, you'll be notified of ventilation timing by "sound" and "light." It measures carbon dioxide with a dedicated sensor, and the color changes to yellow and then red when the concentration rises. By ventilating until it returns to blue, you can always create a comfortable space with clean air. Equipped with a photoacoustic, next-generation high-performance CO2 sensor. The photoacoustic (PAS) CO2 sensor, unlike sensors that react to ethanol (VOC gas sensor method*), is a next-generation optical sensor that utilizes the fact that CO2 reacts to infrared wavelengths, as recommended by the Ministry of Economy, Trade and Industry's "Guidelines for Selecting CO2 Concentration Meters." It accurately detects the carbon dioxide concentration in a closed space. Item | Content ---|--- Operating Temperature/Humidity Range | 0～40℃ / 0～95%RH (no condensation) Storage Temperature/Humidity Range | -20～60℃ / 0～95%RH (no condensation) Detection Target Gas | Carbon dioxide gas (CO2) in the atmosphere CO2 Concentration Detection Method | Photoacoustic method *Detection method using an optical sensor recommended in the Ministry of Economy, Trade and Industry's "Guidelines for Selecting CO2 Concentration Meters" CO2 Concentration Measurement Interval | 5-second intervals for the first 5 minutes after power on / 30-second intervals thereafter USB Input | DC5V 0.5A Batteries | Alkaline AAA batteries x 2 Battery Life (when continuously powered on) | "Bright": Approximately 20 hours / "Standard": Approximately 40 hours / "Dark": Approximately 80 hours (These are reference values and not guaranteed values.) Data Stabilization Time After Power On | Initial stabilization time: Approximately 15 seconds / Complete stabilization time: Approximately 3 minutes External Dimensions | Approximately 82mm in diameter x approximately 60mm in height Weight | Approximately 100g (main unit excluding batteries)