ResMed AirSense 11 filters standard x 6 pack are for use with the AirSense 11 CPAP machine range. You should always regularly check your ResMed Air 11 CPAP sleep apnea machine filter at the back of your sleep machine.
If your not careful what can happen is a build-up of dust can gradually happen over time and then will impede the effectiveness of your CPAP sleep therapy. Also if you live in a dusty environment, or by the sea, you need to replace your ResMed S11 CPAP air filters on a more frequent basis.