Grundy G-Type Keg Coupler, Stainless Steel Construction.
A keg coupler is a major part of any draft beer system. It’s a piece of equipment that connects the gas and beer lines to your keg. Pressurized gas (either CO2 or nitrogen depending on the type of beer being dispensed) flows into the side of the keg coupler through a gas line and the beer flows out through a beer line connected to the top.
All keg couplers are may look the same and work in the same way, but you’ll need to make sure you have the right coupler for the keg you want to serve. The best way to know for sure is to ask the brewer or keg supplier.