PHC RC-x2555C1 DC Barrel Plug Converter, 2.1mm x 5.5mm to 2.5mm x 5.5mm, 3" cord Connector converting from 2.1mm x 5.5mm to 2.5mm x 5.5mm, 3" cord Female Jack - Accepts 2.1mm ID x 5.5mm OD Male Plug - 2.5mm ID x 5.5mm OD ID - refer to inside diameter OD - refer to outside diameter