Fire Angel TST-625-623-E-R Thermoptek Smoke Alarm Combi with 5-year batteries & Escape light Pack of 2. This Smoke Alarm pack contains one unit with an escape light which will ensure you & your family are alerted to danger & are guided to safety. Both units contain Thermoptek multi-sensor technology which pairs the the very latest in optical sensing with thermal enhancement & when compared to single sensor alarms reacts to fire in under half of the time.