Every time you get into your car, you probably reach for your seat belt without giving it much thought. You pull the strap across your body, click the metal buckle into place, and continue with your day. But have you ever noticed the tiny round plastic button attached to the seat belt strap? Millions of drivers see it regularly without knowing why manufacturers put it there.

At first glance, the button might look like a decorative detail or an unnecessary piece of plastic. Some people assume it is connected to the car’s safety sensors, while others believe it helps the seat belt tighten during an accident. Surprisingly, neither explanation is correct. The little button has a much simpler purpose, but removing it can create an inconvenience that drivers quickly notice.

And once you discover what this tiny piece actually does, you’ll understand why something so small has remained part of seat belt designs for years.

Continue below in Part 2.