Product This carbon monoxide detector has a digital display that shows the carbon monoxide level in the room as well as the power level of the device. 1. Concentration exceeds 999ppm: Sound: 4 short alarm beeps LED: Red LED flashes LCD display: “999ppm” 2. 30ppm Concentration exceeds 999ppm: Sound: 4 short alarm beeps LED: Red LED flashes LCD display Screen: “Actual Concentration” 3. Below 30 ppm The LCD display does not light up below 30 PPM. Fault warning: If the carbon monoxide alarm does not work properly, you can find the following conditions: Sound: “Beep/Beep” sound every 30 seconds LED: Green LED does not flash, red LED flashes LCD display: “Err” Quantity: 3 pieces size: 10.5*10.5*4.5cm Package content: 3* CO detector 1. High sensitivity and fast response built-in carbon monoxide detector chip and electrochemical sensor, enough to detect odorless, invisible and deadly carbon monoxide in the air, quick response Can save your life when a fire breaks out at the first time. 2. The safe and visible carbon monoxide alarm detector is optionally equipped with a 3-digit LCD display, and “Err” is displayed on the LCD to indicate equipment failure. “Lb” on the LCS means the battery is low and needs to be replaced. “999ppm” displays on the LCD, indicating carbon monoxide levels exceeding 999ppm, and a loud 85 decibel alarm with LED flash. In alarm mode, it ensures life-saving safety and protects your family from carbon monoxide. 3. Alarm Warning When dangerous levels of carbon monoxide are detected, the red LED light will flash and a loud alarm sound will sound – 85 decibel loud alarm with LED flash. 4. Easy to install and widely used. The Co detector comes with installation accessories, just drill holes in the appropriate position; it can be used to install smoke detectors and carbon monoxide alarms in bedrooms, kitchens, living rooms and other areas with fire risks. 5. Energy-saving 3*1.5V AA battery-powered CO detector (battery not included), low current consumption, long standby time.