Electrochemistry working method & 3 in 1 functionOur carbon monoxide detector is based on the principle ofElectrochemistry, to detect carbon monoxide in the air, capture the weak current generated by electrochemical reaction, detect the concentration of carbon monoxide accurately and quickly by every 2 seconds actual time. . This multi-functional CO detector integrated CO / Temperature / Humidity detection functions,we can see the gas ambient level is good or not actual time. Accurate measuring rangeCO measuring range: 0 - 500 ppm; Humidity measuring range: 20% ~ 80% RH; Temperature measuring range: 14 to 104 (-10 to 40). Large Color 2.2'' circular HD display with value of carbon monoxide / humidity / temperature / and a cartoon face. Super large CO value typeface, You can confirm the carbon CO concentration at a glance. Built-in high capacity 2400mAh battery With 2400mAh battery, this 3 in 1 CO detector can Continue working 90 hours with full charge; still support working when charging, which make this CO detector available working in varies occasions to prevent carbon monoxide-poiso`ning. High performance CO detectorDimensions: 3.26 × 3.26 cm × 1.25 inch; Weight: 4.8 oz. This CO detector is a high quality air quality detector, it features high accuracy, stable performance, jamming prevention, and low consumption. Don't hesitate to choose this beautiful shape carbon monoxide detector, and discard those traditional products without aesthetic feeling! Color indicator light warning & Comfort emoji change & trill Alarm[CO ppm: 0-100, Green indicator light and smile emoji show]; [CO ppm: 100-200, Yellow indicator light and expressionless emoji show warning]; [CO ppm: 200-500, Red indicator light and sad emoji show with trill Alarm]. Widely occasions usingThis 3 in 1 multi-functional carbon monoxide detector can be widely use like home, office, school, camping, picnic, outdoor adventure, in car etc.With portable design, we can put it on the desk, kitchen, near by fireplace, in bedroom, dining, field tent, even we can use it as hand-held air quality monitor. How to test it ? Carbon monoxide is generated in incomplete combustion and dense smoke. We can take it close to a cigarette or burning paper that produces thick smoke. The CO concentration will change and show on the screen. Don't test it by car exhaust or airy place, too low CO consentration can't not trigger sensor to work.