Compatible Machine All M Series All PR System One Series SleepEasy MachinesBenefit of Changing the Air Filter * Simple and consistent replacement of air filters can have an incredible positive effect on sleep and overall health of lung. *Clean air filters are not only good for your health, but also improve and extend the quality of the machine. * Protecting this investment will enable your machine to be used effectively for many more years, and you can save money in the long term through preventative measures.We provide two versions of filters in One Set * 20 Pcs Black Foam Filters * 20 Pcs White Ultra Fine FiltersAbout Black Foam Filters * The black foam filters is to block large particulate matter. * More dense which can better block more particulate matter.* Foam filters should be replaced every two weeks and cleaned with a gentle detergent oftenAbout White Ultra Fine Filters * The ultra fine filters is to block fine particles.*Two layer filter cotton compressed which can achieve better filtration effect. *Harder To Breath Through, But Never Prevent You From Normal Breathing. * It is disposable, and should be discarded and replaced every two weeksSuggestion * Use the black foam filter and white ultra fine filter together to provide the cleanest air * When use this two types filter together, most foam and paper filters will require the paper to be inserted first, then the foam portion.Product Source This filter kit is a generic product supplied by Medihealer!