This device adopts non-dispersive infrared technology (NDIR), with high measurement accuracy, respond quickly, and a resolution of up to 1 that can accurately detect air of Carbon Dioxide (CO2), measuring range 400 - 5000 .The high-definition LED screen allows you to read data faster and more conveniently. There are 4 different color on the screen representing the CO2 concentration level: green is healthy, and red is dangerous. This enables quick recognition of the air quality in your surroundings. stand the CO2 sensor at the vent for 5-10 minutes for data calibration using, and allow 35 seconds for the detector to sense the variation if air quality changes.An alarm will sound at 120dB when CO2 in the air exceeds 1,200 , open the window in time to ventilate or escape the scene if necessary. If the air of CO2 over 1000 , people will feel uncomfortable and work/study efficiency will decrease. In addition, CO2 levels will rise in crowded , CO2 meter will remind you in real time for safety with loud enough sound.With a simple and generous , mini size ( 2.87 x 2.87 x 0.71 inch) makes it easy to carry out, and a built-in 1000 mAh rechargeable battery can continuously work for 8 hours, allowing you to check the air quality anytime and anywhere. This portable CO2 monitor supports USB charging and has a low battery indicator.This mini carbon dioxide monitor is used for grow room, travel, camping, , , hotels, parties, wine cellars, kitchens, bedrooms, offices, schools, agricultural planting, indoor gardens, etc.color:WhiteMaterial:ABSPackage Contents:1 x Portable Capnography Monitor1 CableOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.