3 in 1 Function: This carbon dioxide detector can measure and monitor indoor carbon dioxide level, humidity and temperature in real time, reminding you to ventilate regularly and better protect your health. High-precision CO2 sensor-- The carbon dioxide detector uses non-dispersive infrared (NDIR) technology, high measurement accuracy, fast response (only 1s), resolution up to 1, measuring range up to 0 to 10000 ppm. Its detection accuracy is (40PPMrdg10%). Customized Alarm Value-- This air quality monitor can set the alarm threshold. The alarm threshold range is from 450ppm to 9999ppm, once the CO2 concentration exceeds this value, it will alarm. Press "Enter" key to turn on/off the alarm. Long Standby Carbon Dioxide Monitor-- The CO2 monitor built in 2200mAh rechargeable battery, it can keep working for more than 9 hours when fully charged (support USB charging). Various Usage Scenarios-- It can be installed in various crowded places such as restaurants, commercial venues and facilities, nurseries, schools, social institutions, etc.