“D” system is the most common system available in the U.S., also known as American Sankey. It is used by all the major breweries—Anheuser-Busch, Miller, Molson-Coors, and Labatt as well as most craft breweries.
The keg coupler connects to the keg valve, “tapping” the keg. Both the gas line from the Co2 tank/regulator and the beer hose to the beer faucet attach to the coupler.
