To block even the smallest of particles, the two-pack of Reusable Foam Filters for Respironics M Series Machines are made of polyurethane foam.
Designed for the Respironics M Series CPAP Machines, these filters are washable and reusable. They should be changed every six months.
These reusable foam filters should be washed at least biweekly with water and a mild soap. After washing, rinse thoroughly then allow to air dry before being placed back in the machine. Replace the filter every 6 months, or sooner if damaged or degraded.