Thick, flat foam, greaseless sealing ring ensures maximum contact with your airbox while acting as a breathable gasket for increased air passageCoarse open-pore foam catches airborn dirt, grime, and sandFine open-pore inner foam acts as second filter to trap the smallest particles while ensuring maximum air passageAdhesive withstands repeated cleaningSmaller than stock to increase air space and circulation around filterexclusively formulated adhesive withstands repeated cleaning. even with harsh solvents or gasolinetwin air filters are slightly smaller than stock filters to increase air space around the filter and improve circulation