Apple iPhone Duo

The iPhone Duo is $1,999 and it is the first folding iPhone Apple has shipped. Opened, the inner display is 7.6 inches, with a resolution of 1,398 by 2,034 and the same 1:1.4 aspect ratio as the 5.4-inch, 1,878 by 2,670 outer screen. Both run at 120Hz with peak brightness up to 3,000 nits. The frame is titanium, and the body carries an IP68 rating, which among foldables sold in the US is otherwise found only on the Pixel 11 Pro Fold line.

The engineering worth noting is the inner screen's nanotexture finish, built from more than ten ultrathin layers, which cuts glare and helps disguise the crease that a folding OLED always carries. Apple charges $49 to replace that layer if it is damaged, and warns that picking at it can remove it entirely, unlike rival foldables that flag the film as technician-only during setup. The under-display selfie camera uses an altered sub-pixel layout to let light through without a visible cutout, a trick Samsung introduced on the Z Fold 3 and then dropped.

The camera system is two 48-megapixel rear sensors, a 26mm main and 13mm ultra-wide, giving 2x optical-quality zoom, plus a 12-megapixel Center Stage camera up front. Video tops out at 4K at 120fps. It runs on Apple's A20 Pro chip with a vapor chamber for cooling, and a dual-battery system Apple does not quote in capacity, rated at up to 31 hours of video playback on the inner display and 44 hours on the outer one.

The trade-off is weight. At 254 grams, the Duo is more than 25 percent heavier than the Z Fold 8, even though the two phones carry the same number of cameras and the Z Fold 8's displays are larger. Software is the other open question: Apple's own apps have been rebuilt for the dual-screen format, but plenty of third-party apps, Telegram among them, still run as a portrait window stranded in a wide frame.