Features: A perfect item for protecting your family from the dangers of carbon monoxide Advanced level of protection, easy to read with the digital display, even in low light conditions Displays the level of carbon monoxide the unit is sensing Green LED: Flashes every 30 seconds to indicate the unit is operating properly. The Green LED will also flash before CO reading is taken and when any button is pressed. Red LED : When a dangerous level of carbon monoxide is detected the red LED will pulse and a loud alarm pattern will sound. The carbon monoxide alarm pattern is 4 short beeps, followed by 5 seconds of silence, followed by 4 short beeps with a corresponding red LED flash. This cycle will continue for 4 minutes and then change to 1 cycle every minute until the device is reset or the CO is eliminated. Test/Reset button is designed for weekly testing if it works properly and reset the unit during CO alarm Alerts users when batteries needs to be replaced This alarm is highly recommended to be mounted on a wall surface Compact, lightweight & easy to operate Features: Sensitivity/Alarm Time: Within 60~90 minutes at 50ppm CO concentration; Within 10~40 minutes at 100ppm CO concentration; Within 3 minutes at 300ppm CO concentration LCD Displayer (optional) 4 digits LCD displayer Audibility: 85dB ( at 1m distance ), Frequency 3 - 0.5KHZ Standby Current: