The OSI-RE-SS is usually a reflector- style linear optical beam smoke detector meant to run being a element of fire alarm units. The beam operates totally on the theory of light obscuration utilising an Infra-Pink 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/