The Honeywell NP-200 Photoelectric Smoke Detector is a commercial fire-detection device designed to identify smoke particles and provide early warning of potential fires. It uses a photoelectric sensing chamber that detects changes in light caused by smoke entering the chamber, triggering an alarm signal when smoke levels reach the programmed threshold. Commonly integrated with HVAC s... https://www.partshnc.com/np-200-honeywell-photoelectric-smoke-sensor