SD505-DTS-K, which provides remote annunciation and testing capabilities for the SD505-DUCTR. The SD505-DTS-K uses the same key as the control panel. The SD505-DUCTR is a heavy duty metal housing with a pre installed SD505-APS Analog Photo Electric Smoke Sensor and relay module. When smoke is detected in a duct, the unit communicates the condition to the FACP. The panel, in turn, depending on programming, turns off fans, blowers, and other devices.