Injen Technology X-1021-BR Black and Red 3.5" High Performance Air Filter Double layer cotton gauze not only filters dirt and debris but also works to straighten out air turbulence Pre-oiled from the factory for quick and easy setup Built in velocity stack to help speed up air through intake pipe Predetermined pleat size and quantity to ensure proper filtration and airflow rate Measures 3.5 opening, 6 base diameter, 6.875 height and 5.5 top diameter