The OSI-RE-SS can be a reflector- sort linear optical beam smoke detector designed to work being a component of fireplace alarm techniques. The beam operates primarily on the theory of light obscuration utilising an Infra-Pink beam. OSI-R-SS is a four-wire conventional reflector-type linear optical beam smoke detector to be used https://www.firesense.co.uk/type/conventional-fire-system/conventional-beam-detectors/