Many Hoover Wind Tunnel 3 vacuums don't work properly because the HEPA filter cartridge was NEVER changed! This significantly impedes the flow of exhaust air and can cause the motor to overheat. This is just the right fit for many Wind Tunnel 3 models.Changed that filter and my vacuum is a beast again, a much quieter beast! Also, don't forget that your vacuum cleaner has a washable pre-filter. Keeping the pre-filter clean will extend the life of your HEPA filter. The HEPA filter eliminates irritating exhaust particles containing irritating micro-particles collected from the ground.