Please note: There are two DC Power Cords available for the EverGo Portable Concentrator. To determine which one you need, you will need to check on the SERIAL NUMBER of your EverGo unit. [You can find the serial number on the top of the unit, by unzipping the top section of the concentrator case). For EverGo Serial Numbers below 109500 use DC Cord 900-101. For EverGo Serial Numbers above 109500 use DC Cord 900-120.