This enclosure is a standard 9V battery holder which features an on-off switch on the enclosure and wire leads terminated by a DC Plug 2.1mm.
Battery Holder Case with Cable and Switch
This 9V battery holder allows your battery to snap in tight and holds it in place and has a DC plug output connector. Great for situations where you don't want the battery just hanging. It also has three mounting holes so you can attach it securely to your enclosure.