The OSI-RE-SS is a reflector- form linear optical beam smoke detector created to operate being a component of fireplace alarm methods. The beam operates totally on the principle of sunshine obscuration utilising an Infra-Red beam. OSI-R-SS is really a four-wire conventional reflector-sort linear optical beam smoke detector to be used https://www.firesense.co.uk/type/conventional-fire-system/conventional-beam-detectors/