... Zigbee standard design,they can be used for smart home to detect smog density in the air and provide an alarm ... voltage,AC220V,with 9V back-up batteryTemperature Range,40°F to 100°F (4°C to 38°C)Humidity Range,5%-95% relative humidity ... ,2.06%/ftSound level,85dB/3 meters (10ft)Interconnects,Up to 40pcs smoke alarmHush function,YesDimension,Φ128*38mm AC Powered Standalone ...