Product Description This carbon monoxide detector features a digital display that shows the carbon monoxide level in the room, as well as the units power level. 1. level over 999ppm: Sound: 4 short alarm beeps LED: Red LED flashes LCD Display: "999ppm" 2. 30ppm level 999ppm: Sound: 4 short alarm beeps LED: Red LED flashes LCD Display: "actual concentration" 3. less then 30ppmLCD Display does not lit when less than 30 PPM. Malfunctioning warning: IF the Carbon Monoxide Alarm does not work well, you can find the situation: Sound: "Chirp/beep" every 30s LED: Green LED does not flashe and Red LED flashes LCD Display: "Err" Quantity: 3pcs Size: 10.5*10.5*4.5cm Package Contents: 3* CO detector 1.High Sensitive & Quick ResponsiveBuild-in Carbon Monoxide Detector Chip and the electrochemical sensor, Enough to detect odorless invisible and deadly carbon monoxide in the air, Quick reaction to save your life in the first time when fire hazard occurs. 2.Safety And Visible Carbon monoxide alarm detector With 3 digits LCD displayer is optional,'Err' on the LCD to indicate the unit is malfunctioning. 'Lb' on the LCS to indicate it low battery and need to replacement. '999ppm' on the LCD to indicate CO level over 999ppm And Loud 85 decibel alarm with LED Flash While in the Alarm Mode for the life-saving safety, protect the family from carbon monoxide. 3.Alarm WarningWhen a dangerous level of carbon monoxide is detected the red LED will flashes and a loud alarm pattern will sound--Loud 85 decibel alarm with LED Flash. 4.Easy Installation And Widely UsedCo detector Coming with mounting accessories, just drill holes in appropriate positions, and done; Used for bedroom, kitchen, living room and any other area with a risk of fire danger can be installed a smoke detector and CO alarm. 5.Energy Saving3 * 1.5V AA battery powered CO detector (battery not included), Low Current consumption, Ultra-long Standy time.