The Simplex 4098-9764 is an addressable TrueAlarm multi-sensor detector that combines photoelectric smoke sensing and thermal heat sensing in a single housing. By continuously communicating analog data to a compatible Simplex fire alarm control unit (FACU), the system applies a “TrueSense” covariance algorithm to analyze both activities simultaneously. This dual-criteria evaluation allows the system to drastically reduce nuisance alarms while responding much faster to hot, flaming fires