The OSI-RE-SS is usually a reflector- sort linear optical beam smoke detector designed to operate as being a component of hearth alarm units. The beam operates primarily on the theory of light obscuration utilising an Infra-Crimson beam. Beam smoke detectors might be a vital part of a nicely-designed computerized hearth https://www.firesense.co.uk/type/conventional-fire-system/conventional-beam-detectors/