Battery Operated, Smoke Carbon Monoxide Combo Alarm, Electrochemical Carbon Monoxide Sensor, Alarm Latch To Easily Identify Initiating Alarm After Alarm Condition Has Subsided, Low Battery Latch To Visually Identify Which Unit Is In Low Battery Condition, Alarm Silence To Temporarily Silence Nuisance Alarms, Low Battery Silence To Silence Low Battery Chirp For Up To 8 Hours, Intelligent Sensing Technology Helps Reduce The Number Of Nuisance Alarms, Perfect Mount Allows For Easy Alignment Of Alarm, Dust Cover, Includes Mounting Anchors Screws, Uses 9V Alkaline Battery