RSD Turbine Air Cleaner Black CV/DELPHI for Harley XL 91-11 Exposed filter design offers enhanced airflow Backing plate promotes smooth airflow into carb/ throttle body Built-in internal crankcase breathers Machine Ops, RSDs newest finish, is a fusion of textured natural aluminum and detailed machining that exposes the true beauty of theiraluminum alloy; they then dip the fresh machined parts in a slick clear anodize to protect the surface while keeping its raw aesthetic protected High-volume K&N air filter