Ever noticed that tiny, almost useless pocket inside your jeans? You know the one—just big enough for a couple of coins, but not much else. If you’ve ever wondered about its origin, you’re not alone. While it may seem like a vestigial feature in today’s fashion, this pocket has a history that dates back over a century.

The design of these mini pockets can be traced back to 1873 when Levi Strauss and his business partner, J.W. Davis, filed a patent for “Improvement in Fastening Pocket Openings.” By 1890, the “Lot 501” jeans were born, and with them, the iconic tiny pocket made its debut. These jeans eventually evolved into the 501 jeans we know and love today.

Levi Strauss & Co. historian Tracey Panek recently spoke to Insider about the significance of the pocket. She explained, “The oldest pair of waist overalls in the Levi Strauss & Co. Archives, from 1879, includes the watch pocket.”

Interestingly, this tiny pocket isn’t found on suit trousers, as pocket watches were typically kept in the vest pocket of a formal jacket. Levi Strauss himself is said to have carried his pocket watch in the vest of his business suit.

Fast forward to today, and the pocket has become more of a nostalgic feature. While it no longer serves its original purpose, Levi’s keeps it in place to preserve the design integrity of their early jeans. According to Panek, the jeans’ design has largely remained unchanged since its inception, with a brief exception during WWII when the metal rivets were removed to conserve materials for the war effort.

It’s worth noting that the tiny pocket isn’t technically the fifth pocket on Levi’s jeans. That distinction goes to the back-left pocket, added in 1901. The original 19th-century Levi’s jeans had only one back pocket, located on the right side.

Over the years, other fashion brands have adopted the mini pocket concept, sometimes placing it in different spots or concealing it within a larger pocket. The pocket serves as a subtle reminder that the jeans are meant for casual wear, not to be paired with formal attire.

As for what you can actually use the tiny pocket for today? People have found it handy for holding small items like rings, matches, coins, or even keys. So, while it may not be practical for pocket watches anymore, it certainly holds a place in fashion history.