The OSI-RE-SS is actually a reflector- type linear optical beam smoke detector meant to run like a component of hearth alarm techniques. The beam operates totally on the theory of light obscuration utilising an Infra-Pink beam. OSI-R-SS can be a 4-wire conventional reflector-variety linear optical beam smoke detector for use https://www.firesense.co.uk/type/conventional-fire-system/conventional-beam-detectors/