Portable CO Detector Carbon Monoxide Detector, Mobile CO Warner Carbon Monoxide Warning Detector, CO Meter with Temperature & Humidity Display, for Travel, Camping, HD09-GreyMULTIFUNCTIONAL & PORTABLE This CO detector is a 3 in 1 combined carbon monoxide, temperature and humidity meter. The compact and portable design makes this CO detector very suitable for use in cars, motorhomes or travel. It can protect you from carbon monoxide poisoning anytime and anywhere. High Precision Carbon Monoxide Sensor This CO detector uses the principle of electrochemical reaction to quickly and accurately measure CO concentration. The built-in carbon monoxide sensor has a high measurement accuracy and a long service life. It is certified with the EN-50291 (EU standard for CO detectors) and offers high reliability. LCD Screen & Acoustic Alarm: All the readings are updated every two seconds and displayed on a high resolution 2.45 inch LCD screen, which makes the CO concentration visible and easy to read. If the CO concentration exceeds 50ppm, this CO detector emits an acoustic alarm. Built-in rechargeable lithium battery: the built-in 1000 mAh lithium battery can hold this CO detector in standby mode approx. Keep working continuously for 70 hours. This CO detector can also work during charging and provide accurate readings. You can always leave it connected to a USB power supply to continuously monitor CO concentration if necessary. Standby Mode After one minute of inactivity, this CO detector automatically turns off the backlight of the screen and goes into standby mode for energy saving. In standby mode, the CO sensor continues to work and continuously monitors the CO concentration. ATTENTION: This is a carbon monoxide (CO) detector, not a carbon dioxide (CO2) detector. If you turn on this detector in a normal living environment with clean air, it is normal that the carbon monoxide indicator is 0, as there is no carbon monoxide in clean air.