S4-771-S Gent Dual Optical Heat Multisensor with sounderHoneywell Gent S4 771 S Dual Optical Heat Sensor Sounder BS 5839 1: 2025 Introduction The Honeywell Gent S4 771 S is a dual optical heat sensor sounder designed for areas where a standard smoke detector may be too sensitive on its own, but where you still need fast, intelligent fire detection and local alarm signalling. As part of the Gent Vigilon S Quad range, it combines dual optical sensing, heat detection, an integral sounder, and a built in short