The Disposable Ultra Fine Filters are used with all DreamStation CPAP and BiPAP machines. These filters, which come in a blue frame that is permanently attached to one another (and thus cannot be separated) can also work with other devices that have standard 40 mm connectors. Disposable filters are essential to maintaining your CPAP therapy by removing dust, pollen, and tobacco smoke particles from the air you breathe. Replace your disposable CPAP filters every 30 days, or sooner if you notice a drop in performance. Replace your reusable CPAP filters every 90 days to keep debris from building up Disposable filters cannot be washed and should be replaced monthly or sooner if dirty. The permanent fine filter and blue frame cannot be separated.