Universal Web Nanofiber Dry Filter (X-1017-BB) by Injen. Shape: Round Tapered. Flange Inside Diameter: 3in. Top Outside Diameter: 4in. Base Outside Diameter: 6in. Height: 5in. Pleat QTY: 45. This air filter is a major breakthrough in air filtration technology. It features a revolutionary synthetic nanofiber filter media that increases airflow, while capturing and holding more dirt than conventional air filters. It never needs oiling and is guaranteed for 4 years or 100,000 miles, whichever comes first.