The tattletale wireless Smoke Detector can be placed up to 500 feet away from the tattletale base unit. It uses photoelectric technology to detect smoke and uses an integrated fixed 135F temperature rate-of-rise sensor to detect heat. The tattletale base unit does not need to be armed for the smoke detector to report an event. The supervised sensor monitors its own sensitivity and operational status and will notify the tattletale of an alarm event, low battery, lost signal & tamper.