Check the listing for details. System Sensor D4120 4 Wire Photoelectric Duct Smoke Detector. Condition: New – Open box, Made in Mexico. Listed at 124.99 USD. System Sensor D4120 4 Wire Photoelectric Duct Smoke Detector Brand new, open box. Box opened only to confirm contents. The System Sensor D4120 4 Wire Photoelectric Duct Smoke Detector is a reliable and efficient smoke detection device designed for commercial and industrial facilities. Manufactured by System Sensor in Mexico, this model offers a high level of protection against smoke hazards. The 4 wire design ensures easy installation and maintenance, making it a convenient choice for facility managers looking to enhance their fire protection equipment. With its proven track record of effectiveness, the D4120 smoke detector is a valuable addition to any business or industrial setting seeking to safeguard against potential fire hazards.