Working smoke alarms cut the risk of dying in a home fire by 50% and that"s important because a home fire starts every 83 seconds! The faster you know about a fire the faster you can start moving your family outside, The FamilyGard battery-operated smoke alarm is easy to install and has many unique features, It uses ionization smoke sensing technology with dual ionization chambers and has wide openings for easy smoke entry, The smoke alarm also features a test button for weekly testing and a convenient hinged cover, 85-decibel horn and an audible low batter indicator, It contains a missing battery guard which ensures a battery is placed inside the smoke alarm, A 9-volt battery is included, Compact design measures 4 3 4"" x 6"", Boxed UL listed, Length: 4, 50"", Width: 4, 50"", Height: 2"", SKU: hstz5510