The Surface Duo is essentially a smaller version of the Surface Neo, a dual-screen tablet not unlike Microsoft's Courier concept. The prototype shown today features two 5.6-inch displays that unfold to form an 8.3-inch tablet. Unlike the gimmicky folding phones being pushed by other companies, Microsoft's solution is two separate screens, meaning you won't have the durability issues that plague folding screen... and you can fold them completely back, just like a 2-in-1 laptop, for even more usage modes. Surface Duo, as you may have guessed, won't run a modified version of Windows like the company's old phones did. Instead, the device will be built on Android. Interesting, right?