[COMPATIBLE and PERFECT FIT WITH VARIOUS SLEEP EQUIPMENT MACHINES]- Fits for All Philips Respironics M Series, for PR System One Series, for SleepEasy Machine! Each filter to fit your machine precisely. [PREMIUM QUALITY CLEANFLOW TECHNOLGY]- The reusable black foam filter is to block large particulate matter, the white ultra fine filter is to block fine particles. Use them together to provide the cleanest air. [KEEP YOUR MACHINE RUNNING LONGER AND MORE EFFICIENTLY]- Not Only Do Our Filters Help Keep Your Lungs Clean, But It Also Prevents Dust, Dirt, and Other Buildups from Entering Your Motor. [30 PCS ECONOMICAL SET]- Include 15 Pcs Reusable Black Foam Filters and 15 Pcs White Ultra Fine Filters, replace your filter every two weeks is recommended. Colour: black and white Material: sponge and cotton Package Contents: 15 x Reusable Black Foam Filters 15 x White Ultra Fine Filters Only the above package content, other products are not included. Note: Light reflection 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.