This fitting is typically used on the end of the liquid line that attaches to the keg couplers.
This fitting has a check valve built in. This check valve prevents liquid from draining out of your beer line when it's disconnected so it's a dry break.
The most common fitting to put on the thread of the back of this fitting is the Duotight 8mm female to 5/8" female push in fitting which you can see here. Alternatively you can use the hex nut, barbtail and a 5/8" seal and then use a hose clamp. If you wanted to use these fittings then you will need the 5/8" hex nut, then you can attach one of these barbtails along with a 5/8" seal:
KL05081 Angle Barbtail - To suit 4-6mm ID Tubing
KL05098 Straight Barbtail - To suit 4-6mm ID Tubing
KL05104 Straight Barbtail - To suit 6-8mm ID Tubing
KL05111 Straight Barbtail - To suit 8-10mm ID Tubing
KL05128 Straight Barbtail - To suit 10-13mm ID Tubing
The K-Lok adaptors/quick disconnects are compatible with Andale (Snaplok), Lancer Pacific (Fatlock) and other brands of draft beer quick lock fittings that are often seen in commercial pubs and bars.
These check valves are designed to fit liquid lines which would then typically fit into your keg coupler.
They are made with 5/8 male threads. Depending on what size of gas line you are using you can choose from multiple different hex nut and barbs or our push in fittings to go on the back of these.