Pen manufacturers add this hole not for aesthetics but for safety reasons.

Children, and sometimes adults, have the habit of biting or holding pen caps in their mouths.

If such a cap accidentally gets lodged in the airway, the hole allows some airflow — which can save a life until medical help arrives.

This is especially important for school-age children who often play with stationery.

That’s why international safety standards, such as ISO 11540, require pen caps to have a ventilation hole.

It ensures minimal air circulation even if the cap is accidentally swallowed or inhaled.

Of course, a cap with a hole might seem less “airtight,” but it still protects the ink cartridge from drying out.

Most importantly, it reduces the risk of choking — which can be critical in emergencies.

So next time you see that tiny hole in a pen cap, know that it’s not a manufacturing defect but a carefully designed safety feature that can save lives.