You’ve worn button-down shirts for years — maybe even every day — but have you ever noticed that small fabric loop stitched at the back, just below the collar ?

It’s not a flaw. It’s not a leftover from manufacturing.

This tiny detail — commonly known as the “locker loop” — has a rich, practical, and surprisingly stylish history that spans naval decks, Ivy League campuses, and modern fashion runways .

So what is it for? And why is it still on shirts today?

Let’s unravel the mystery behind the back loop on button-down shirts — and why this small feature says a lot about tradition, function, and subtle style.

What Is the Locker Loop?

The locker loop (also called a hanger loop , sweater loop , or backstay ) is a small strip of fabric sewn vertically between the shoulders on the inside of a dress or casual shirt.

While it’s most commonly found on Oxford cloth button-downs (OCBDs) , it also appears on some polos, blazers, and even women’s shirts.

At first glance, it seems pointless — but its origins are deeply rooted in practicality and prestige .