My Hoover wind tunnel vacuums (I have one upstairs and one downstairs) were both losing suction so before ordering 2 new vacuums I checked the hoses ( I had a Christmas snowflake blocking the hose!) and then looked at the filter. I didn't even know the car had 2 filters! I clean the top rounds fairly regularly because I have a dog but when I realized there are 2 filters in there I looked at the HEPA filters and both were dusty and dirty. So I ordered 2 sets of filters and they arrived in 2 days (nice not having to go to the store during COVID), installed them in under a minute and now both machines are running better - more suction and quieter!