There are two forms of preset temperature detectors: linear detectors, which monitor the temperature during a location, and location detectors, which observe the temperature in one particular area. The PAD200-DUCTR is developed and created to fulfill all area specifications, plus the NFPA rules with regards to duct smoke detectors. Air https://www.firesense.co.uk/type/addressable-fire-system/addressable-beam-detectors/