Respironics Pollen Filters (2 in a pack) for M Series and System One CPAP and BIPAC devices (1029330) with (6) RP Ultrafine Filters (part 1029331)Be sure that you are breathing in fresh, clean air through your CPAP machine. These Reusable CPAP Filters for M-Series, 50 & 60 Series, System One fit Philips Respironics M-Series, System One 50 or 60 Series CPAP and BiPAP machines. The convenient 2-pack means you will have spare CPAP filters on hand whenever you need to wash the one you are using. You can rewash and use these filters 2 to 3 times before replacing. CPAP America is your one-stop-shop for all of your sleep apnea needs!