Widgets and Beer. Co2 is different then Nitrogen, Co2 carbonates nicrogen doesn't. That is the idea behind beergas isn't it, as well as the reason nitrogen is used in draught stout. It flows through and produces a nice head. I know there is more to it, but nitrogen and the widgets are for making that creamy head we associate with draught guiness, otherwise we could just give it a rough pour and call it a day.