Oxygen Humidifier Adapter Tube for connecting oxygen concentrator to humidifier. Humidifier bottle adapter has a swivel nut on one end that makes for an easy fit on the humidifier bottle. Screw the male thread grip into the oxygen inlet port located on top of the humidifier bottle. Connect your oxygen concentrator tubing extension to the oxygen outlet port located on the bubble humidifier. This humidifier adapter fits most O2 water bottles and oxygen concentrators. 90 Degrees connection tube specially designed for 5L oxygen generator.