Output Filters for the Inogen One and Inogen One G2 are intended to protect the user from inhalation of small particles in the product gas flow. On both the Inogen One and Inogen One G2 the output filter is conveniently located behind the removable cannula nozzle fitting and should be inspected and replaced on an annual basis. These filters are compatible with all Inogen One and Inogen One G2 Oxygen Portable Oxygen Concentrators.Inogen requires that this filter be replaced between patients. The output filter may be replaced by the equipment provider or by the owner using the Output Filter