There's two varieties of fastened temperature detectors: linear detectors, which monitor the temperature all over a region, and location detectors, which watch the temperature in a single precise site. The PAD200-DUCTR is intended and constructed to satisfy all community prerequisites, in addition to the NFPA restrictions about duct smoke detectors. https://www.firesense.co.uk/type/addressable-fire-system/addressable-beam-detectors/