The OSI-RE-SS is a reflector- style linear optical beam smoke detector made to function like a part of fire alarm systems. The beam operates totally on the basic principle of sunshine obscuration utilising an Infra-Crimson beam. OSI-R-SS is a four-wire conventional reflector-sort linear optical beam smoke detector for use in https://www.firesense.co.uk/type/conventional-fire-system/conventional-beam-detectors/