The System Sensor RTS2 and RTS2-AOS multi-signaling accessories are designed for use with System Sensor InnovairFlex 4-wire conventional duct smoke detectors only. The accessory has two bicolored LEDs that indicate the sensor status of up to two connected duct smoke detectors. The key switch on the unit can be used to select a connected duct detector sensor (either sensor 1 or sensor 2), and the selected sensor can be tested or both sensors can be reset simultaneously using the test/reset button. LED status indications include Standby (green blink), Trouble (amber), Maintenance (amber blink) and Alarm (red).