K&N Custom Racing Air Filter - Rectangular Carbon Fiber 4in Air Box w/ 2.75in Air HornLight weight yet durable, K&N's Generation 2 Carbon Fiber Air Boxes are a must for any racer currently using traditional multi Siamese stacks. Constructed from ultra lightweight carbon fiber these filters provide ample air flow for your racing needs. They come with air horn seals to provide better sealing and easy installation. As with all K&N air filters, Generation 2 Carbon Fiber Air Boxes are washable and reusable. Simply use K&N cleaner and oil to