Filters are the first line of air filtration defense for your CPAP system and should be replaced when dirty or every month. Hypoallergenic filters trap large floating particles such as cat hair and dander.</br></br>Product Description</br></br>The Disposable Hypoallergenic Filters for AirSenseTM 10 and AirCurveTM 10, and machines includes filters used for the S9 series by ResMed.</br><br/>http://www.amazon.com/gp/product/B01HFIRKAM