We clean our filter after every use but over the years we've still used the original filter so we decided to look for a replacement. This filter matches the letter "T" and makes the vacuum cleaner work like new. We remove it after each use and take it outside. If you grab one end and bang the railing with the other, you'll be amazed at how much dust and dirt falls out. I use an old toothbrush to finish cleaning between the creases. We bought four so it should last a long time.