Minimal.

These are the designs with no single subject: stone, silk, sand, smoke, a gradient. Nothing in them competes with the lock-screen clock, and nothing important gets cut off whichever display or orientation you are using.

That matters more on the Duo than on a regular phone. iOS shows the whole image on the inner display in landscape but only the central strip on the cover and in portrait, so a busy picture can look like two different wallpapers. A texture looks the same at every crop.

Free download · one 2892×2034 master; iOS crops both screens.