3-in-1 Handheld Carbon Dioxide Meter — real-time CO2, temperature, and humidity monitoring for clearer indoor air decisions What this device does Measures carbon dioxide concentration, ambient temperature, and relative humidity in real time so you can assess indoor air quality quickly and reliably. Displays CO2 on the same screen as temperature and humidity using a two-line LCD for simultaneous, at-a-glance readings. Provides immediate visual status with green, yellow and red backlight warnings so you know when air quality requires attention. Why you need it Detects poor ventilation: identify rooms with elevated CO2 that indicate inadequate fresh air exchange so you can improve ventilation or reduce occupancy. Supports health and comfort: track temperature and humidity alongside CO2 to create a more comfortable, productive indoor environment and reduce complaints. Saves time and battery: automatic shut-off conserves power between measurements for long-term, low-maintenance use. Key features and performance 3-in-1 functionality: carbon dioxide, temperature, and humidity measurements in a single handheld instrument. Two-line LCD: simultaneous display of CO2 and temperature/humidity for fast interpretation and easy record-taking. Color-coded backlight (green/yellow/red): instant visual alerts that communicate air quality status without needing to read numbers. Auto shut-off: conserves battery when the meter is not in use to extend operating time. Portable design: compact, handheld unit for easy transport between rooms, sites, or vehicles. Durable construction and intuitive controls: designed for routine use in homes, offices, classrooms, and maintenance checks. Practical applications Classrooms and lecture halls: monitor CO2 to reduce stuffiness, decide when to open windows, or adjust HVAC settings to lower transmission risk and improve student focus. Offices and meeting rooms: check air quality before and during gatherings to maintain comfort and alertness among employees and visitors. Building maintenance and HVAC diagnostics: use rapid CO2 and humidity measurements to verify ventilation performance, troubleshoot systems, and validate improvements. What to expect in everyday use Fast, readable results on a two-line LCD, with an obvious color cue when values cross recommended thresholds. A battery-powered, handheld meter you can carry to any indoor space for spot checks or routine monitoring. Reduced guesswork about indoor air — clear metrics that let you take targeted actions to improve ventilation and comfort. This meter combines essential IAQ measurements, clear visual warnings, and battery-saving convenience in a compact handheld tool suited for home, office, educational, and professional use.