The small button on a car seat belt might seem insignificant, but it plays a vital role in ensuring both safety and convenience. Known as a stop button or retainer button, this tiny plastic piece prevents the metal latch plate—the part that clicks into the buckle—from sliding too far down the strap when the seat belt isn’t in use.

Without this button, the latch plate would slide all the way to the belt’s base, making it harder to reach when it’s time to buckle up. This simple yet effective feature keeps the latch plate in an accessible position, saving both time and effort.

Most seat belts are equipped with two stop buttons. One is positioned near the latch plate to prevent it from sliding toward the floor, while the other is placed higher on the strap to stop it from moving too far up toward the shoulder. Together, these buttons ensure the seat belt remains properly aligned and ready for use.

While durable, these buttons can wear out or break over time. Fortunately, replacements are easy to find at auto parts stores or online, and they can be installed at home with basic tools.