aFe18-01501Air Filters - Universal FitConstructed with 100-percent polyurethane bottom with a metal top, this non-oiled OE replacement filter provides years of hassle free service. Three Layers of Progressive Synthetic (Dry) Media for Maximum Convenience. Washable and reusable for multiple cleaning cycles, the tall open evenly spaced pleats provide excellent dust holding capacity for longer service cycle between cleanings. Integrated urethane bump seal insures tight, no leak seal over the life of the filter.aFe TOP Racer racing filters feature a patented single-piece design which allows airflow in from the side and top of the filter. The one-piece (TOP) filters eliminates leaks and sealing failures under changing pressures. TOP Racer filters are available with PRO 5R media which is constructed of 5-layers of progressive cotton gauze to produce maximum flow, or with aFe PRO Dry S filter media which is 2-layers of synthetic media that requires no oils for cleaning for maximum convenience. Both are washable and reusable.