The Edwards Signaling Duct Detector is a photoelectric smoke detector designed for installation in air ducts. It operates on 16-30V DC and provides a Form C alarm contact rated at 10A @ 125VAC. The duct housing is constructed of 18 gauge steel with an insect-resistant screen and NEMA 1 rating for indoor use. It features an LED indicator and test switch on the cover. The detector head can be easily removed for cleaning or replacement. This duct smoke detector provides early warning of smoke conditions in HVAC ducts in commercial buildings.