What type of tap is associated with the U coupler?

The U coupler is specifically designed for use with beers that are packaged in kegs using this type of fitting, most notably including those that produce stouts and porters. The most famous example is Guinness, which uses the U coupler to dispense its iconic nitro beers. This system employs a unique mechanism that allows for the proper carbonation and dispensing of these beers, resulting in the creamy texture and rich flavor profile that are hallmarks of styles like dry Irish stout.

Other types of taps, such as those for Heineken, Budweiser, or Coors, utilize different coupler systems (specifically the D and A couplers, among others), which are better suited for lagers and other styles of beer. Knowing the specifics of which coupler corresponds to which beverage is crucial in professional beer service, as using the wrong coupler can lead to poor beer quality and presentation.