ResMed S9 and AirSense 10 Style Hypoallergenic Filters (12 pack)<div style="text-align: left;"><strong>[Product Information]</strong><ul><li class="showHiddenFeatureBullets"><span class="a-list-item"> 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. </span></li></ul></div><img src="http://ecx.images-amazon.com/images/I/318Ja9Cw5kL.jpg" noproxy>