The 915 final filter sold here is a generic replacement manufactured by Envirocare. This filter features a 3 layer allergen protection to effectively remove 99.7% of the smallest particles and allergens from the air. It is recommended to replace your filters every 6 months, or sooner if you notice your vacuum losing suction. The filter comes 1 per pack. The Hoover final filter sold here is designed to work with the following model vacuum cleaners: Hoover Wind Tunnel Bagless Model Vacuum Cleaners Hoover Self-Propelled Upright Model Vacuum Cleaners