1. Accurate CO Detection: Our Carbon Monoxide Detectors meet UL2034 standards for accurate sensing and high stability. It alert if the carbon monoxide in the air is higher than the safe concentration. 2. Loud Alarm: When a dangerous level of carbon monoxide is detected, the red LED flash and emit a loud alarm that can be heard even through walls, reminding you to make your as soon as possible to avoid danger. 3. Visible LED Display: 3-digit display, when a carbon monoxide leak is detected, the current value be displayed according to the concentration (note that it not be displayed when it is below 30ppm), an intuitive display for greater peace of mind. 4. Easy Installation: Powered by 2 x AAA batteries (not included), slid to remove the back cover and replace the batteries. The back is equipped with wall mounting holes, can be fixed by the included screws, safe and fast. 5. Alarm Standard: 50ppm, alarming within 60 to 90 minutes; 100ppm, alarming within 10 to 40 minutes; 300ppm,