The reason why soda can rings have a hole: this is how the stay-on tab works

The next time you crack open a refreshing beverage, take a closer look at the pull tab. You might notice a small, unassuming hole near the base. This little indentation, often mistaken for a place to hold a straw, serves a far more critical purpose: it’s the key to the smooth operation of the stay-on tab.

Contrary to the name “pull tab,” the modern design doesn’t involve pulling. Instead, it utilizes a stay-on tab or a lift tab. This innovation emerged in the 1960s as a safer alternative to the earlier pull tabs, which could detach completely and pose a choking hazard.

The stay-on tab relies on a clever combination of leverage and mechanics.

Here’s where the hole comes in

During manufacturing, the top of the aluminum can is pressed and folded inwards to create a tight seal. This crimping process naturally leaves a small indentation – the hole we see.

A separate piece of metal is stamped into the familiar tab shape. A crucial element is a hook that curves underneath the can’s top rim. This hook is designed to fit perfectly through the hole created during crimping.

When you push down on the lift tab, the force isn’t directly prying open the can. Instead, the hooked end under the rim acts as a fulcrum. Imagine a see-saw – the hole is the fixed point, and the hooked end acts like the short end of the see-saw.

As you press down on the tab, the leverage created by the hook pivots against the hole. This upward force lifts the opposite end of the tab, which is cleverly designed to wedge under the can’s lid. The prying action of the tab pries the lid open, allowing access to your beverage.

A critical advantage of the stay-on tab is that it remains attached to the can. This eliminates the choking hazard of detached pull tabs and keeps the tab from littering the environment.