The Red Filter'. As used in Formula 1, Le Mans, Moto GP and World Superbike. Designed as an direct replacement, no hassle fit, upgrade for the OEM paper air filters. Manufactured with a metallic mesh which contains multiple cotton layers of oiled filtration material. This allows improved air flow, sufficient for stock to all-out performance applications. To further help prevent small impurities enter the engine filtration oil is used to create a 'sticky' barrier which allows air flow but helps retains small particles up to 7 micron. All filters are precision made and continuously checked during production for the highest obtainable quality. Filters are washable and reuseable. EU made.88-22 XL Sportster with OEM 29042-04C SE or 29066-03 SE air cleaner kit (NU)