There are plenty of non-Apple foldables out there, but finding a perfect match is tricky.

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While Apple's first-ever foldable phone is the subject of plenty of attention, the Cupertino tech giant was actually well behind Android phone makers to the category. The Duo makes a strong entrance, but with major players like Samsung, Google and Motorola at it for years, there is no shortage of foldable smartphones in this day and age.

Each of these three competitors offers a book-style foldable phone, like the Duo, which essentially turns any smartphone into a mini tablet. As they're larger than the alternative flip-phone designs, they're a great choice for multitasking, reading, streaming shows and more.

Even when we limit the focus of this article on the passport-style options, there's no clear-cut Android counterpart for the Duo. Each of the candidates differs on size, cameras, durability and more.…