This WindTunnel Bagless Secondary Filter fits below the Twin Chamber® Dirt Container. It is visable throught the hole in its cover plate. The filter measures 5 5/8" x 2 1/2" x 1/4" with rounded ends. There is a 3/8" hole in the center through which the cover plate screw passes. While the earlier filters were green as shown, Hoover's later ones are white.   For similar products see our list of current Hoover Vacuum Supplies.