K&N's RK Series Air Cleaner Assemblies are designed to get more horsepower from your Harley-Davison motorcycle. These air cleaner assemblies replace the stock air filter and backplate with an oversized K&N Air Filter and custom aluminum backing plate. K&N's RK Series Air Cleaner Assemblies are designed to give you an increase in power and long service intervals critical for distance rides. This complete assembly fits inside the OE air cleaner cover maintaining stock appearance while providing outstanding airflow.