This is a great DC power jack/connector for projects in an enclosure. This is a common barrel-type power jack for DC wall supplies, in a panel-mount form factor. These are compatible with our DC wall supplies and have a 5mm jack, with a 2.1mm center pole diameter. Simply drill the proper size hole in your enclosure, slide the jack through and secure it with a nut. Panel mount jacks are also useful in preventing mechanical stress from hanging power cables damaging your board.
The inside diameter of the included washer is about 8mm, a 5/16" drill bit works nicely to mount these jacks.