The air duct smoke detector shall be a System Sensor InnovairFlex D4120A Photoelectric Duct Smoke Detector. The detector housing shall be ULC listed specifically for use in air handling systems. The flexible housing of the duct smoke detector fits multiple footprints from square to rectangular. The detector shall operate at air velocities of 100 feet per minute to 4000 feet per minute (0.5 to 20.32 meters/second). The unit shall be capable of controlling up to 50 air handling systems when interconnected with other detectors. The detector shall be capable of providing a trouble signal in the event that the front cover is removed. It shall be capable of local testing via magnetic switch, test button on the cover, or remote testing using the RTS151KEYA Remote Test Station. Terminal connections shall be of the strip and clamp method suitable for 12-18 AWG wiring..