Used from a system that had to be upgraded.  This is a top-notch Fire Alarm Photo Electric Smoke Detector from Hochiki. It is a highly efficient device that guarantees top-notch performance. The product is built to last, and it comes with an allan key that ensures you have no issues during installation. It is a must-have for anyone looking to ensure the safety of their business or industrial facility. The device belongs to the Fire Alarms category and is part of the Fire Protection Equipment, Facility Maintenance & Safety, and Business & Industrial subcategories. The model number of this device is SLG-24F, and it is perfect for anyone who needs a reliable smoke detector.  The base is HS-21D HA9.  You are buying 2 detectors, 2 bases and one allan key for this price.  SHIPPING IS FREE!!!