The 1/2 inch threaded plug is used on all of our fermenters except the Mini Me. It is also used on our MiniMash Lauter Tun and the MiniHot Liquor Tank.
The fermenters and tanks which require plugs, are delivered with the plugs. The threaded ports are used for a thermometer below the label as well as for various ports which may not always be in use.
Remember to always use teflon tape!