Coarse, open-pore foam, The Twin Air® Air Filters For Offroad catches airborne dirt, grime and sand. Fine open-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. Slightly smaller than stock filters to increase air space around the filter and improve circulation. Fused outer and inner elements prevent dirt and grime from being lodged between layers, this can be a problem with inferior 2-piece designs. Trapped particles can restrict airflow, and if dirt works its way into your engine, a pinhead-sized granule will gouge your cylinder, piston and rings like a bullet. Thick, flat foam, greaseless sealing ring ensures maximum contact with your airbox, while acting as a breathable gasket for increased air passage.