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 AIRFILTER FIRE RES - FOR KIT 150231C HONDA CRF250R 22-24 CRF450R 21-24 CRF250RX 22-24 CRF450RX 21-24