The OSI-RE-SS is usually a reflector- type linear optical beam smoke detector intended to run for a part of fireplace alarm devices. The beam operates totally on the basic principle of sunshine obscuration utilising an Infra-Purple beam. OSI-R-SS is usually a four-wire conventional reflector-form linear optical beam smoke detector to https://www.firesense.co.uk/type/conventional-fire-system/conventional-beam-detectors/