Compatible with M Series, PR System One Series, and SleepEasy machines. Each filter is designed to fit your machine precisely. Premium quality CleanFlow technology: reusable black foam filter blocks particulate matter; disposable white ultra-fine filter captures fine particles. Use together for optimal air filtration. Helps keep your machine running efficiently by preventing dust, dirt, and debris from entering the motor. 30-piece economical set includes 15 reusable black foam filters and 15 disposable white ultra-fine filters. Replace filters every two weeks for best performance. Color: black + white. Material: sponge + cotton. Package contents: 15 x reusable black foam filters, 15 x disposable white ultra-fine filters. Light reflection and display differences may cause slight color variation between image and actual item. Measurement allowance: +/- 1-3 cm.