The OSI-RE-SS can be a reflector- kind linear optical beam smoke detector designed to run as being a ingredient of hearth alarm systems. The beam operates totally on the principle of sunshine obscuration utilising an Infra-Red beam. OSI-R-SS is a 4-wire conventional reflector-style linear optical beam smoke detector for use https://www.firesense.co.uk/type/conventional-fire-system/conventional-beam-detectors/