The System Sensor® InnovairFlex™ 4-WIRE PHOTOELECTRIC DUCT SMOKE DETECTOR features a pivoting housing that fits both square and rectangular footprints and mounts to round or rectangular ductwork. This unit senses smoke in the most challenging conditions—airflow speeds of 100–4000 feet per minute, temperatures of –4°F to 158°F, and humidity of 0%–95% (non-condensing). A plug-in sensor head offers false alarm immunity and simple installation, testing, and maintenance, while the cover design isolates the sensor head from the low-flow feature for simple maintenance.