Kidde 21005927 Firex Wire-In Smoke Alarm With Battery Backup, 85 DB At 10 FT Loud, 60 HZ Operating Frequency, 120 VAC Operating, 80 MILAMP Operating, 40 - 100 DEG F Operating, Environmental Conditions: 5 - 95 PCT Relative Humidity (RH), Ionization Sensor, Dimensions: 5 IN Diameter X 1-3/4 IN Depth, Flashing LED Display, Mounting: Single Gang Electrical Box, Up To 4 IN Octagon Box, Included: 9 V Battery, Sensitivity: 0.5 - 1.06 PCT/FT, UL 217, NFPA 72, (Chapter 11) The State of California Fire Marshall, NFPA 101 (One And Two Family Dwellings), Federal Housing Authority (FHA), Housing And Urban Development (HUD)