MX DC Female Connector Chassis Type 2.5mm x 5.5mm (MX-2248A)

2.5mm x 5.5mm is the step up from the ubiquitous 2.1mm barrel, used on adapters that are often rated for somewhat higher current and on equipment manufacturers want to physically distinguish from the smaller, more common size. This connector mounts through a panel exactly like its 2.1mm sibling, giving an enclosure a fixed, proper power entry point instead of a loose cable penetration, but matched to the slightly larger pin size so a 2.5mm adapter seats fully and makes solid contact rather than wobbling in an undersized jack. Worth keeping on hand alongside the 2.1mm version since a lot of adapter boxes don't say which size they are until you measure the pin.