arlen ness ac stg in big skr crhm backing 600 302All New Next Generation Backing Plate Design, Increases Horsepower and Torque, Aluminum Backing Plate That Features Zero Flat Surfaces, Every Angle of the Intake is Designed to Promote Airflow, One Piece Aluminum Top Filter Place With Integrated Air Venturi Performance filters are made from black pre oiled cotton for the best in airflow and filtration, filter is washable and reusable