The S3500/A1R is a cost effective and aesthetically pleasing non-addressable rate of rise 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.