Final Filter-Hoover U5399-900 WindTunnel Lite Upright Vacuum

\015 I am looking for a part # or any info to help me find a replacement final filter for this vacuum. Not the filter under the bag. This would be the filter that is placed into the side door that slides open and closed. The previous filter I had was multi-layered, but I had to trim it to fit the door. The length is 6 5/8 inches; but this size seems to only be for the NON-self-propelled Hoovers. I could have sworn the Hoover U5399-900 WindTunnel Lite Upright Vacuum was self-propelled. Frustrated with these crazy vacuum manufacturers! (and myself for throwing away the manual years ago, hahaha)\015 – Hoover U5399-900 WindTunnel Lite Upright Vacuum