IKEA might be best known for its array of ready-to-assemble furniture like beds, bookshelves, and desks, as well as the wafting scent of Swedish meatballs. But the popular household goods franchise also sells a steady number of coffee mugs. Most are unremarkable, including the spectacularly named VARDAGEN, and therefore never go out of style. But the VARDAGEN does have one odd feature. The 3.25-inch off-white stoneware mug comes with a chip on the bottom. Why?

According to Reader’s Digest, the chip has an official IKEA term: It’s called a drainage gate, and it has a very specific purpose.

The drainage gate was implemented so water wouldn’t collect on the bottom of the mug in a dishwasher. Since mugs are loaded upside-down, water has a tendency to pool on the bottom, which could conceivably result in a slightly splashy mess when unloading.

Because the “chip” is so smooth and uniform, it’s unlikely too many people mistake it for a damaged product. You can also find the drainage gate in the VARDAGEN teacup and saucer set.

[h/t Reader’s Digest]