Optical detectors can “see” a fire from a long distance without the need for smoke or heat to get to the detector. Light travels extremely fast so the detector “sees” (reacts) extremely fast to flaming fires that can be up to 215 feet (65m) away and only 1 foot 2 inches (0.3m2) in size. This feature makes optical flame detectors very effective in large, open, or critical areas where other fire detection methods would not work.