The PF40 kit (Item #210 - 50 - 00 - 00) can be added to any IQAir system for superior coarse filtration. This helps to extend the life of the unit's standard pre - filter element. Kit includes 3 pre-filtration pads. A filter pad may be washed several times before it needs to be replaced. Not compatible with the accessories FlexVac, VM FlexVac, VM InFlow and InFlow W125.