Apple Inc.’s (NASDAQ:AAPL) first foldable iPhone could deliver one of its boldest design changes yet — but getting there may require the company to resurrect an old technology and sacrifice some of its most recognizable premium features.

Foldable iPhone May Trade Face ID for Touch ID

Apple is expected to unveil its first foldable iPhone at its Sept. 9 event, with reports suggesting the device could be marketed as the iPhone Ultra and priced at around $2,000 or more.

The rumored device could measure just 4.5 mm thick when unfolded, creating major engineering constraints within the phone’s two slim halves.

That reportedly means there may not be enough space for Apple’s TrueDepth hardware, which powers Face ID. Instead, Apple could bring back Touch ID by embedding the fingerprint sensor in the side-mounted power button.