The Real Purpose of the Small Hole at the Bottom of a Padlock

Padlocks aren’t the only everyday items designed with hidden features. Some screwdrivers fit into the circular opening of a wrench to create extra leverage in tight spaces. Clothing often comes with a small fabric swatch—not just for testing detergents, but for repairs or matching thread. Even brass doorknobs have purpose beyond decoration; the metal naturally resists bacteria.

Vehicles also include clever design details, like the tiny arrow next to the fuel gauge that tells you which side the gas tank is on. Even iconic products hide functionality—Heinz’s “57” mark shows the ideal spot to tap to release ketchup from a glass bottle.

From household objects to cars and tools, these small details remind us that smart design often hides in plain sight. Noticing them helps us appreciate just how much thought goes into making everyday life a little easier.