I didn't realize how dirty (to say the least) my old filter had gotten. I haven't changed it since I bought the vacuum, hmm a few years ago around 5. When I changed the bag I noticed that it was caked with dirt and pet hair. I'm surprised I didn't kill my vacuum cleaner! The sucking got really bad, but it was so gradual that I didn't even notice. After replacing the filter with this new one (which fits perfectly) I feel like I have a new vacuum cleaner! And 2 are coming so I'll last another 10 years lol.