Exhaust filter for Hoover Non Self Propelled WindTunnel upright vacuum cleaners. Also fits some Hoover WindTunnel Supreme, Hoover Tempo, Hoover Fold Away, and Hoover EmPower upright vacuums. The filter measures 6 5/8"" x 3 5/16"" x 1/2"" and has a single white layer. Previous versions of this filter had a green, yellow, and white layer. Genuine Hoover part - 40110004, which is also referred to as filter 38766009. For optimum performance and extended motor life, replace vacuum filter every 18 months.