why do cans of guinness have balls in them
Widget (beer) A widget is a device placed in a container of beer to manage the characteristics of the beer's head. The original widget was patented in Ireland by Guinness. The "floating widget" is found in cans of beer as a hollow plastic sphere, approximately 3 cm in diameter (similar in appearance to table tennis ball, but smaller) with at least one small hole and a seam. The "rocket widget" is found in bottles, 7 cm in length with the small hole at the bottom.[1]
Widget (beer) The widget in the base of a beer glass works by creating a nucleation point, allowing the CO2 to be released from the liquid which comes into contact with it, thus assisting in maintaining head on the beer. This has become increasingly popular with Fosters, Estrella and others using them in public houses in the UK.