Genuine Hoover WindTunnel with Power Drive Exhaust Filter - is currently on backorder. You may still purchase now though and we'll ship as soon as more become available.
The filter fits inside the filter door on the side of self-propelled WindTunnel uprights including U6445906, U6471900, U6476900, U6476910. The filter measures 10 7/16" x 3 5/16" x 1/2".