The iPhone Duo uses Super Retina XDR displays on both sides, with ProMotion and Always-On support. Apple rates peak outdoor brightness at 3,000 nits for both screens. A nano-texture finish on the inner panel reduces glare and makes the fold crease less visible, according to Apple. Grade 5 titanium forms the enclosure, while the precision hinge uses more than 100 components. Apple also gives the iPhone Duo an IP68 rating for water and dust resistance. Apple designed iOS 27.1 to work across the phone’s open and closed configurations. Split View lets users run two apps side by side, a first for the iPhone. Users can also open two windows of the same app and save app pairs for later use. The inner screen can show two Home Screen pages and a vertically scrolling Today View. Touch ID sits in the side button and works whether the device is open or folded.