Universal Clamp-On Air Filter. KandN XD air filters use a Deep Pile Design, Extra Fine Weave Grade Cotton and alternate geometries for added efficiency and capacity for off-road conditions. This extra thick filtering medium provides the increased protection demanded by high dust conditions while continuing to provide the performance necessary to stay in the front of the pack. The XD Cotton medium was developed for the extreme conditions encountered by race teams in the Baja 1000. This real world testing is combined with testing performed at KandN;s own Dust Retention Laboratory in conformity with the ISO 5011 test protocol. XD Cotton Air filters can be cleaned in the same way as KandN;s original cotton air filters.