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]