Vyaire AirLife Bacterial/Viral Filter REF:001851 - Filter for CPAP/BIPAP - Case of 50. This filter fits most home CPAP and BIPAP machines and fits in line between the machine and hose. This Bacterial/Viral filter traps bacteria and viral particles by electrostatic attraction and its dense makeup. Filters up to 99.9995% of expiratory bacterial content and 99.995% of expiratory viral content. Individually packaged single use filters. Each filter good for 24 hours of operation. Case contains 50 filters. Please see pictures for details. Contact if you have questions. Free domestic shipping.