25 mm external in-line filter with filtering element, for use with Comelit ASD series aspirating smoke detectors. For installation in applications that may be particularly dusty or dirty, such as sawmills, scrapyards, etc., in order to significantly extend the life of the smoke sensors inside the machine, as well as the airflow sensors and suction device used in the ASD. The internal filtering elements should be replaced regularly (product number RFC911). Operating temperature 0 +60