Manufacturer Name: Fenwal Product Number: 35-615526-223 OEM Part Number: 35-615526-223 Product Description: 24V Dsi 3-Try 30Spp 7Stfi Weight:0.7lbs/317.51g The 35-615526-223 is a Fenwal Delay Smoke Detector (DSI) used in various HVAC systems for fire detection. It operates on 24 volts DC power and employs a three-step detection process to minimize false alarms. https://www.partshnc.com/35-615526-223-fenwal-24v-dsi-3-try-30spp-7stfi