Thick, flat foam, greaseless sealing ring ensures maximum contact with your airbox while acting as a breathable gasket for increased air passageFeatures: Coarse open-pore foam catches airborn dirt, grime, and sand Fine open-pore inner foam acts as second filter to trap the smallest particles while ensuring maximum air passage Adhesive withstands repeated cleaning Smaller than stock to increase air space and circulation around filter exclusively formulated adhesive withstands repeated cleaning. even with harsh solvents or gasoline twin air filters are slightly smaller than stock filters to increase air space around the filter and improve circulation