Replacement Columns for Inogen One G4Replacement columns are essential for keeping your Inogen One G4 portable oxygen concentrator in top shape. These replacement columns contain sieve beds that filter out nitrogen from the air to deliver high purity oxygen, making them a crucial part of your devices performance. Over time, these sieve beds wear out, which is why regular replacement is key to maintaining consistent oxygen delivery. When your G4 displays the replace columns alert, its