If you’ve ever taken a carton of milk out of the fridge and noticed a small round dent on the side of the jug, you’re not alone — and you’re certainly not the only one who’s never given it much thought.
At first glance, that dent might seem like a manufacturing defect or just a random indentation in the plastic. It’s easy to assume it’s a flaw or the result of handling during shipping. But in reality, that small dip is no accident. It’s actually a smart piece of engineering designed with a very specific purpose.
This subtle feature helps the jug withstand changes in pressure, prevents it from bursting if the milk expands, and even offers a bit of shock absorption if the container is dropped. It’s one of those hidden design choices that quietly make our everyday items safer, more durable, and more reliable—without us ever having to think about it.
