About this item 3 in 1 Carbon Monoxide Monitor – Detects carbon monoxide (0-999 PPM), temperature (14-122℉), and humidity (0-95% RH) Loud & Accurate Alarm – Uses a high-sensitivity electrochemical sensor. When CO levels exceed 150 PPM, it triggers a sound and light alarm with a loud 85 dB alert. Plug & Play – No installation required, simply plug it in and start using. Compact & Clear Display – LCD screen provides clear, high-definition readings, even in low-light conditions. Wide Application – Suitable for bedrooms, kitchens, living rooms, bathrooms, apartments, garages, offices, restaurants, hotels, RVs, Yacht and more.