The S3500/B is a cost effective and aesthetically pleasing non-addressable fixed temperature heat detector. These detectors are designed for open area protection and provide the best warning of fire in locations which are not suitable for smoke detection technologies. A centrally positioned LED indicator provides 360° visibility of detector activation and an in-built magnet test feature allows easy activation to verify operation of the detectors. A selection of connection bases make the unit compatible with most conventional control equipment.