Honeywell's V-Plex Addressable Photoelectric Smoke Detectors are designed to provide open area protection and to be used with compatible UL or ULC-listed Honeywell control panels that support V-Plex technology. The detectors incorporate a state-of-the-art optical sensing chamber and an advanced microprocessor. Built-in Drift Compensation algorithms automatically maintain proper operation at factory calibrated detection levels, even when sensitivity is altered due to the presence of contaminates settling into the unit's chamber. The 5193SDT/A also features a restorable, built-in, fixed temperature (135°F/57.2°C) thermal detector.