It’s one of those tiny car features that drivers often notice without ever wondering why it exists. Between the two cup holders on some center consoles, you may find a pair of raised plastic tabs separated by a narrow opening. At first glance, they can look like nothing more than part of the cup-holder design, but that small gap often has a surprisingly useful purpose.

The opening is commonly designed to hold a smartphone upright. By sliding the bottom edge of your phone into the space between the two raised supports, you can keep it standing instead of leaving it loose in a cup holder or on the passenger seat. But while this simple discovery explains the strange slot, there is another reason many drivers completely overlook it—and once you understand what the designers intended, the feature suddenly makes perfect sense.