-The perfect item to protect your family from carbon monoxide. -It is strongly recommended to install this alarm on the wall. It is compact, light and easy to operate. -The carbon monoxide level sensed by the display device. -Green LED: flashes once every 30 seconds, indicating that the device is operating normally. The green LED will also flash before taking the CO reading and when any button is pressed. -Red LED: When a dangerous level of carbon monoxide is detected, the red LED will flash and a loud alarm will sound. -The test/reset button is designed to test whether it is working properly every week and reset the device during CO alarms-Remind the user when the battery needs to be replaced-The carbon monoxide alarm mode is 4 short beeps, then mute for 5 seconds, and then 4 short beeps with corresponding red LED flashing lights. This cycle will last for 4 minutes and then change to 1 cycle per minute until the device is reset or the CO is eliminated. Specification: White colorSensor: Electrochemical CO sensorSensitivity/alarm time: Within 60~90 minutes under 50ppm CO concentration; Within 10-40 minutes under 100ppm CO concentration; Within 3 minutes at 300ppm CO concentrationLCD display (optional): 4-digit LCDStandby current :