I don't know of a threaded barrel package from KJW that includes the hop up/inner barrel. It is entirely possible, as KJW parts are available from KJW TW for cheap and they sometimes offer to assemble stuff if I order parts that belong together.
If not, that is just a one piece outer barrel with extended/threaded tip on the muzzle end for attaching suppressors. I can't exactly remember, but I think the one I got was a 14mm+ (also the threading that KJW suppressors are made in... I think). The KJW threaded barrels are available in both 14mm- and 14mm+, though. Very simple to install if you have to do it on your own. You will definitely get it cheaper from KJW directly though, if you're willing to wait about a month for a small envelope of parts to arrive.