Why do Pen caps have a tiny hole at the top? The hidden reason will leave you shocked https://ift.tt/X7kQVhL

The hole in pen caps balances air pressure. When you close a pen, the cap traps air inside. Without a vent, pressure differences could make the cap hard to remove or even cause ink leakage.

from Zee News :India National https://ift.tt/w3qrIxO