The beam operates primarily on the theory of sunshine obscuration applying infrared. The OSI-RI detector is a mixed transmitter/receiver which can be right linked to an clever detector circuit in LiteSpeed® or CLIP manner. If You're not still registered, be sure to enter your email address beneath and click "Proceed" https://www.firesense.co.uk/type/addressable-fire-system/addressable-beam-detectors/