Apple this week unveiled an iPhone that unfolds like a book to expand its screen size and closes up to fit in your pocket. It’s the biggest physical change to the iPhone’s design in nearly two decades. But even though they’ve been around for years, foldable phones aren’t particularly popular.

They’re expensive, awkward and not as durable as regular smartphones. So why did Apple build one? The simple answer is that the novel design of today’s foldable phones could help re-establish the high end of the phone market. They are meant to stand out in a sea of standard-issue, if-you’ve-seen-one-you’ve-seen-them-all smartphones.

The quintessential rectangular smartphones have gotten so good over the years that the most expensive models priced upward of $1,000 have become nearly indistinguishable from their cheaper counterparts. Foldable phones, on the other hand, are attention getters. And for their price, they’d better be: Apple’s iPhone Duo will cost $1,999 when it arrives in October to compete with Samsung’s $1,900 Galaxy foldable.

Apple’s foldable handset is arriving at a moment when people will need extra persuading to upgrade to a new phone. IDC said it expected the chip-shortage-induced price increases to contribute to a 17 percent drop in worldwide smartphone sales this year — the steepest annual decline in history. However, sales of foldable phones could grow 12 percent to 22.9 million because of the iPhone Duo’s arrival, the research firm said.