[High-quality materials] The CPAP filter is made of high-quality materials, which can effectively filter fine particles, dust and pollen without affecting air circulation. perfect replacement for CPAP machines [Wide compatibility] This CPAP filter is very suitable for most CPAP machines, suitable for M series, PR System One series [Provide good protection for your machine] These CPAP filters help prevent dust, dirt and other fine particles from entering the CPAP machine, which can extend the life of the machine. [Perfect filter combination]-20 reusable black foam filters and 20 disposable white ultrafine filters. Including a total of 40 Pcs air filters, it is recommended to replace the filter every two weeks, one set can meet your needs throughout the year [Provide the cleanest air ] and your loved to keep your lungs healthy and away from potential diseases White cotton sheet: 4.5*2.3cm Black cotton sheet: 4.5 * 2.5cm Color: black + white Material: sponge Package Contents: 20 pc * White cotton sheet 20 pc * Black cotton sheet Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.