Kidde 0919-9999 Battery Operated Wireless Interconnectable Smoke Alarm, 85 DB At 10 FT Loud, 9 VDC Operating, 40 - 100 DEG F Operating, Environmental Conditions: Up To 85 PCT Relative Humidity (RH), Ionization Sensor, Dimensions: 5-3/4 IN Diameter X 1-1/4 IN Depth, LED Display, Mounting: Wall Or Cei