This Pressure Filler Cap makes transfering beer to a bottle easy! If you keg your beer and want to take a few bottles for you to drink or your friends to try, this is the perfect piece of equipment for you. It can also be used to carbonate your beer or water or used to clean your beer lines. This fits both the black/liquid and grey/gas ball lock disconnects and has a barb tail that fits 6mm tubing if you wish to use this when filling bottles. Click this link to a video of how this works https://www.youtube.com/watch?v=ianeB7VJj-A