This Respironics in-line bacteria filter fits between the CPAP machine and the CPAP tube. It provides cleaner air for those who suffer from allergies. Manufactured by Respironics, this bacteria filter can be used with ANY brand of CPAP or BiPAP machine. The inline filter will fit all standard machines from:Fisher & PaykeDeVilbissRespironicsResMedPuritan Bennettand Many More! Restrictions: Please note the following restrictions on use for this itemInline Bacterial Viral filters should not be used with humidified CPAP & BiPAP units.Use of Inline Bacterial Viral filters may adversely effect auto sensing on Auto-CPAP systems especially at low pressures (below 7cm).