Compatible and with a variety of sleeping equipment: fits all, PR system one series, sleeping machine Each filter to fit your machine exactly. Clean Flow Technology: Reusable black foam filter is used to block particulate matter, disposable white filter with highly fragmented is to block fine particles. Use together for the cleanest air. Keep your machine running and more efficient: Not only do the filters help keep your lungs clean, but they also prevent dust, dirt and other motor build-up from entering.50 pcs. Economical set: includes 25 pcs. Reusable black foam filters and 25 pcs. Disposable white filters with highly fragmented filters, it is recommended to replace the filter for two weeks. If you're in a particularly dirty or dusty environment, you may want to change your filters more often. This one set fully satisfies at least a year's needs. Name: CPAP FiltersType: for CPAP FiltersRole: White+BlackMaterial: SpongeSize: 4.5x2.3cm/4.5x2.5cmPackage Content:50*Cotton FilterOnly the above package content, other products are not included. Note: The light and different displays may cause the color of the item in the picture to be slightly different from the real thing. The allowed measurement error is +/- 1-3cm.