Ultraviolet control cabinets dissipate real heat from ballasts and ignitors into a largely sealed enclosure. A blinded filter is the usual first cause of a cabinet running hot: airflow falls gradually, so temperature-related faults appear long before anyone suspects the filter. Replace on a routine interval rather than on symptoms. This filter suits the Rittal SK 3323.100 enclosure fan unit, so it can be identified and sourced against the Rittal part number as well as ordered here. Wedeco was founded in Herford, Germany in 1976 and is now a Xylem brand.