Genuine Hoover HEPA Exhaust filter cartridge fits Hoover Windtunnel Air UH70400.Genuine Hoover HEPA filter cartridge for the Hoover Windtunnel Air Lightweight Upright model UH70400. This filter is located directly underneath of the dirt cup assembly. It's very important that this filter not get wet in any way. Hoover recommends to remove the filter every 30 days, and tap it against the side of your trash can to remove any debris. This is a very durable filter, and should only need replacing every 2-3 years, unless you, or someone in your home suffers from breathing issues such as asthma, or has allergies. The more often this filter is replaced, the better airflow your motor will have, prolonging the life of your motor with increased filter replacements. Genuine Hoover HEPA Filter Cartridge, Part Number 303902001. Fits Hoover Windtunnel Air Model UH70400. DOES NOT FIT HOOVER MODEL # UH72400