The OSI-RE-SS is usually a reflector- style linear optical beam smoke detector designed to operate as a component of fireplace alarm units. The beam operates totally on the basic principle of sunshine obscuration utilising an Infra-Crimson beam. Shut/span> You can not access this page as this solution is just not https://www.firesense.co.uk/type/conventional-fire-system/conventional-beam-detectors/