Apex Medical iCH Reusable Filter - It is very important to keep the airflow to your CPAP machine free of debris, a CPAP machine is similar to a house furnace as it pulls air in and filters it out. The Apex iCH Reusable Black Foam Filters are used to filter the air that flows through. This filter keeps harmful allergens from going into your lungs. The filters are considered reusable because they are able to be cleaned