The National Fire Protection Association (NFPA) has published codes, standards, and recommended practices for the installation and use of this product. It is recommended that the installer be familiar with theses requirements, with local codes, and any special requirements of the local authority having jurisdiction. For further information, consult NFPA 72 and 90 A requirements. 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 bi-colored 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). With the key switch selected, there is also the capability of obtaining a sensitivity measurement of the selected sensor using the SENS-RDR sensitivity reader (sold separately).