[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. Using them together helps provide cleaner air. [HELP MAINTAIN MACHINE PERFORMANCE] - These filters help keep your machine running efficiently by helping to prevent dust, dirt, and debris from entering the motor. [30-PIECE ECONOMICAL SET] - Includes 15 reusable black foam filters and 15 white ultra-fine filters. Replacement every two weeks is recommended. 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. Measurement may vary by +/- 1-3 cm.