FireAngle Thermistek Wireless Interlink Heat Alarm is uses predictive technology to monitor the rate of temperature increase and alerts you to the danger quicker. Thermistor heat sensing element for accuracy, reliability and stability. Locate feature when a network of alarms goes into alarm pressing the test button on any of the units will silence all but the initiating alarm. Heat alarms are for use in places where a smoke detector is not suitable, for example where there are high ambient air temperatures, high humidity or in dusty and dirty environments. e.g. garages, lofts and kitchens. 10 year sealed in power pack removes the need to replace the batteries.