The removable metal columns provide a way to service your Inogen One G4 without having to send in the product for repair. Sold and used as a pair, the columns contain the sieve beds that convert normal air with lower levels of oxygen concentration to supply a high concentration of oxygen. These sieve beds wear down after prolonged use.
The life of the (sieve) columns is guided by the “replace columns” alarm and is typically within a year. In certain operating conditions, earlier replacement may be required. The Inogen One G4 will let you know when it is time for replacement.