K&N Custom Racing Assembly Carbon Fiber 4in Air Box w/ Base and Hardware - LargeLight weight yet durable, K&N's Sprint Car Style Air Boxes are a must for any racer currently using traditional multi Siamese stacks. Constructed from ultra light weight carbon fiber K&N's Sprint Car Style air box provides ample air flow for your racing needs. As with all K&N filters, it is a washable and reusable air filter. Simply use K&N oil and cleaner to service your filter.