Cygnus lithium heat detectors are an integral part of the system, providing essential detection in and out of working hours on all types of construction projects. These highly tested and extremely quality detectors work in the radio mesh like any other device and will help transmit and receive all other radio messages from other alarms to help site wide radio performance. Using a matched pair of thermistors to sense heat, one thermistor is exposed to the ambient temperature, the other is sealed. In normal conditions, the two thermistors register similar temperatures, but, on the development of a fire the temperature recorded by the exposed thermistor will increase rapidly, resulting in an imbalance of the thermistors and causing the detector to change to the alarm state. With the new GSM functionality from the GSM control panel, you can be assured your site is protected 24 hours a day 7 days a week. Detector comes with an 85 decibel sounder.