Auxiliary Oxygen Port (Serial numbers commencing with R, N, or B): Your concentrator is supplied with an auxiliary oxygen port which might be used to fill oxygen cylinders with an FDA-cleared cylinder filling system that's meant to use oxygen from a concentrator to fill a cylinder. Also compared to other https://allhealthmarket.com/product/medical-supplies/portable-oxygen-concentrator-generator/oxygen-concentrator-machine-camping-use-oxygenator-driving-oxygen-bar-with-24-hours-battery-lasting-oxygen/