Duct temperature sensor / air duct temperature sensor including mounting flange, with passive output. Duct resistance thermometer THERMASGARD® KTF-1 with passive output, connecting head made of impact-resistant plastic, enclosure cover with quick-locking screws, and plastic mounting flange. This duct sensor is particularly designed for temperature measurement in airflows and for the detection of temperatures in gaseous media, e.g. in ventilation and air conditioning ducts.