There’s a ball in a can of Guinness to recreate the smooth, draught‑style pour and creamy head you’d get from a pub tap, using nitrogen gas rather than just carbonation. That plastic ball is called a widget , and it’s a small, hollow sphere that helps give Guinness its signature texture and cascading foam when you open and pour the beer.

What the “ball” actually is

  • It’s a small, hollow, food‑grade plastic sphere with a tiny hole in it, nicknamed a widget.
  • Guinness started using this technology in the late 1980s to mimic the draught experience in cans and bottles.

How it works inside the can

  • During canning, Guinness adds nitrogen and seals the can under pressure; some beer and gas get forced into the widget through its tiny hole.
  • When you open the can, the pressure suddenly drops, the widget “vents” nitrogenated beer back into the can, creating a burst of tiny bubbles that form that thick, creamy head as you pour.

Why Guinness uses nitrogen

  • Nitrogen makes smaller, smoother bubbles than carbon dioxide, giving Guinness its velvety mouthfeel and characteristic cascade effect in the glass.
  • This gas mix is what bartenders use on draught lines; the widget is basically a mini, built‑in draught system for at‑home cans.

Extra cool facts and “latest” chatter

  • The widget concept took years to perfect and has even been described as an award‑winning packaging innovation for preserving that classic Guinness pour.
  • Beer geeks and forum threads still regularly pop up with people shaking an empty can, hearing the rattle, and asking what the “mysterious ball” is—then discovering it’s just the widget doing its job.

TL;DR: The ball in a can of Guinness is a nitrogen “widget” that releases gas when you open the can, creating the creamy head and smooth texture that make canned Guinness taste like it came fresh from the tap.

Information gathered from public forums or data available on the internet and portrayed here.