The HFA1138 is an air filter from Hiflofiltro, the well-known company that makes air and oil filters for motorcycles, scooters and ATVs. An OEM replacement – Built to specifications that match the standard air filters. High-quality materials – It uses premium paper or foam filters for optimum air flow and filtration. Increased air flow – It guarantees better engine performance without sacrificing filtration. A direct fit – No modifications are needed for installation. Compatibility – Designed for specific motorcycle models (check compatibility on the manufacturer's page).