Apple’s long-awaited foldable phone, the Duo, was announced during the company’s Surprise and Shine event on Wednesday, and its most unusual engineering detail is the hinge. Chief hardware officer Johny Srouji said AI algorithms are used in manufacturing to match each individual hinge with its best-fit housing for perfect alignment. A confocal laser then progressively scans the topology of every unit, and up to 25 micro layers of a custom photopolymer are 3D printed to eliminate residual waviness.

Apple also gave the Duo a custom nano-texture finish to reduce glare and reflections, plus a multi-layer lamination strategy aimed at increasing durability. The article notes that foldables by design undergo twice as much wear as traditional devices, and most in the category have suffered significant degradation and lower durability than conventional smartphones. Whether Apple’s protections are enough to keep the Duo in peak condition over the long run remains to be seen, as the report includes no independent durability testing or additional device specs.