The Fire Resistant Air Filter - KTM/Husqvarna EXC-F500 2017-2023, FE501 2017-2023 (FOR KIT 154220C) is part of the latest collection from Twin Air.. Specifically designed for modern 4-stroke applications, these triple layer filters have an additional flame retardant inner layer for extra protection. Twin Air filters are slightly smaller than stock filters to increase air space around the filter and improve circulation. The resulting increase in air volume around the filter improves circulation within the airbox. More air means more power for your engine. Flow bench tests have proven that Twin Air filters provide increased airflow while reducing the filters tendency to clog.. Features: Coarse open-pore foam catches airborne dirt, grime and sand. Fine, pore inner foam acts as a second filter to trap the smallest particles while ensuring maximum air passage. Exclusively formulated adhesive withstands repeated cleanings, even with harsh solvents or gasoline. Thick, flat foam, greaseless sealing ring ensures maximum contact with your airbox, while acting as a breathable gasket for increased air passage. Fused outer and inner elements prevent dirt and grime from being lodged between layers. . Manufacturer part number: 154220FR.