Hypoallergenic Filter for the AirSense 10 and ResMed S9 Series
Amazon.com: CPAP Filter– Premium Ultra Fine Disposable Replacement Filters for CPAP Machines – Compatible with ResMed Air 10, Airsense 10, Aircurve 10, S9 Series and More! 30 Filters : Health & Household
ResMed S9 VPAP Auto Inner and Outer Filters Replacement - iFixit Repair Guide