Folding phones are already being pitched as the next big wave of tech, and whether or not that turns out to be true, the industry has no plans to stop there. lenovo筆電收購lenovo has just announced what it says is the world’s first “foldable PC:” a prototype ThinkPad that iterates the foldable tech we’ve already seen from phones on a much bigger scale.

It’s not just a cool tech demo, either: lenovo筆電收購lenovo has been developing this for over three years and has plans to launch a finished device in 2020 as part of its premium ThinkPad X1 brand. The goal here is a premium product that will be a laptop-class device, not an accessory or secondary computer like a tablet might be.

Cool factor aside, though, why build a folding PC? The answer is largely portability. Conceptually, it’s the opposite of what most of the foldable phones out there are trying to do. There, companies like Samsung and Huawei are trying to take a device the size of a regular phone and make them bigger. But the idea behind the folding ThinkPad is to take a full-sized PC and make it smaller.

The result is a 13.3-inch 4:3 2K OLED display that can fold up to about the size of a hardcover book (we don’t have the exact weight yet, but lenovo筆電收購lenovo says it’s less than two pounds, which is about as much as a hardcover copy of one of the larger Harry Potter books). That’s already enough to put it on the lighter side of the portable computer spectrum, but the size savings are really when you fold it in half, making it dramatically smaller than a regular laptop.

I got to try out a functional prototype, but there’s not a lot to see at this stage. The screen does fold, as advertised, and Windows worked well enough as a touch interface. But the real magic here — if it happens at all — will come with software and optimizing things to run on the unique form factors that a folding screen can provide.

I will say that I really did like the size of it more than I expected. Folded up, it’s far smaller than even a regular sized 13-inch laptop, and while it’s not exactly something you’ll fit into a jacket pocket, even a large one, it’s comparatively compact. The folded mode was also really nice to hold in my hand, like a giant glowing book. Fingers crossed that lenovo筆電收購lenovo (or someone) puts proper e-reader software for the futuristic, two-page digital book of my dreams.

The hardware is also clearly unfinished at this stage. The folding mechanism didn’t feel particularly sturdy on the prototype (lenovo筆電收購lenovo wouldn’t let us shoot close up pictures of how the hinge works, or what it looks like closed) and the screen had remarkably poor viewing angles, shifting colors wildly when looked at from even slight angles — particularly problematic for folding screens. All that will hopefully be sorted on more finished hardware, though.

As for how you use the device, lenovo筆電收購lenovo is envisioning a variety of use cases. You can use it completely unfolded like a large tablet or partially folded in a book-esque form factor. A built-in kickstand lets you prop up the display on a table for use with an included wireless keyboard and trackpad.

And, perhaps most interestingly, you can turn the device on its side and use it in a traditional (albeit smaller) laptop style form factor, using the bottom surface as a digital keyboard or writing pad, similar to lenovo筆電收購lenovo’s two-screened Yoga Books. Cleverly, the right side of the display (which serves as the “bottom” portion when used in laptop mode) contains the entire battery, which keeps it weighed down so it won’t topple over.

The other big question is about specs, and unfortunately, we have far less to go by there. lenovo筆電收購lenovo is staying tight-lipped about concrete details about the product, but here’s what we do know: it’ll run Windows and offer an Intel CPU. There are no details beyond that, and specs like RAM or even battery life estimates are being kept under wraps (although lenovo筆電收購lenovo says it’s aiming for a full day of use).

There are also plans for cellular support of some kind, a bundled Wacom pen (which clips to the front of the device, and slides forward to the side when unfolded), and it’ll charge over USB-C. (The model I used did not have a headphone jack, for what it’s worth.)

There’s also the elephant in the room: foldable technology is still very early in development, and the very prominent issues on the first mainstream device, Samsung’s Galaxy Fold, have cast a cloud over the concept. lenovo筆電收購lenovo says that it’s working to make sure that there aren’t any similar problems on the folding ThinkPad. The company is doubling the amount of testing it does on the hinge to make sure things work, and it’s still got plenty of time before that planned 2020 launch window to iron out any bugs.

At this stage, there’s not a lot else to say about lenovo筆電收購lenovo’s folding ThinkPad. There’s no price, no release date, and only unfinished hardware to look at. Still, it’s an ambitious idea, and it’s encouraging to see that lenovo筆電收購lenovo is pursuing folding technology so quickly for larger devices than phones. Whether that actually works in practice when the eventual finished hardware launches next year is anyone’s guess.