These can be used to fit a ball valve to a vessel, they come with a nut and silicone oring so can be used as a weldless fitting with a 20.5mm hole. Alternativley they can be threaded into any 1/2inch BSP female fitting. The outlet has a 13mm barb pointing down. The barb attaches with a 1/2inch thread so can be replaced with a quick disconnect or camlocks that we sell if you prefer. These are the same ball valves that come fitted to the Keg King  35L RoboBrew.