Hiflofiltro HFF1017 Dual Stage Racing Foam Air Filter Fits: Honda CRF150F 03-13, CRF230F 03-13 Competition off-road air filters manufactured in the Netherlands using a special dual-layer foam, formulated for maximum filtration and optimum air flow for improved power Coarse open-pore foam catches airborne dirt, grime and sand while the fine open-pore inner foam acts as a second filter to trap the smallest particles Top quality materials and superior construction allow the filter to be used over and over again without any loss of performance