Kidde Fire 9V Photoelectric Smoke, Hush (formerly model PE9)

Power Source:9V Battery (included), Audio Alarm:85dB at 10ft, Temperature Range:40F to 100F (4C to 38C), Humidity Range:5 PCT -95 PCT relative humidity (RH), Sensor:Photoelectric, Size:5IN diameter x 1.5INdepth, Weight:.8lbs, LED:Red, normal operation