[COMPATIBLE WITH VARIOUS SLEEP EQUIPMENT MACHINES] - Fits all Philips Respironics M Series, PR System One Series, and SleepEasy machines. Each filter is designed to fit your machine precisely. [PREMIUM CLEANFLOW TECHNOLOGY] - The reusable black foam filter helps block large particulate matter, while the white ultra-fine filter helps capture fine particles. Used together, they help provide cleaner air. [HELP MAINTAIN MACHINE PERFORMANCE] - These filters help keep your machine clean by reducing dust, dirt, and other debris from entering the motor, which may help extend the life and efficiency of your device. [30-PIECE ECONOMICAL SET] - Includes 15 reusable black foam filters and 15 white ultra-fine filters. Replacement every two weeks is recommended for optimal performance. Color: Black + White Material: Sponge + Cotton Package Contents: 15 x Reusable Black Foam Filters 15 x White Ultra Fine Filters Note: Light reflection and differences in display screens may cause slight variations in color between the image and the actual item. Measurement error allowed is +/- 1-3 cm.