LCD Displayer with a Blue Ground Light * Loud 85 decibel alarm. Permanent Carbon Monoxide Sensor. * The Alarm Sound Pattern is Three Short Alarm Beeps. The Red LED Will Flash While in the Alarm Mode. One chirp every 30 seconds in an indication that the battery is low (need replacement) (green LED still flashes once every 30 seconds). * Package Content: 1X Floureon Carbon Monoxide Alarm / 2X Screws / 1X English User"s Manual. * Easy to install. Instructions were detailed, informational, and well written.