Tyler Lizenby/CNET

I've opened and closed foldable phones hundreds of times by now. But even after reviewing the Galaxy Fold (twice), playing with Huawei's Mate X and bending slim concept designs, nothing has prepared me for TCL's prototype dual-hinged phone, which folds in three parts and opens into a huge, 10-inch tablet.

The most remarkable thing about TCL's phone is that the hinges themselves move in different directions. The DragonHinge fold in, like a book, or like the Galaxy Fold, while the Butterfly Hinge folds the opposite way.

The two hinges create a zigzag shape as you open and close the device, a silhouette in Z. It looks like an accordion. Or a taco holder. And I have to get my greedy hands on it to give it a fold, one panel at a time: Open. Folded over once. Completely folded up into a triple-stacked sandwich so that the exposed panel becomes the TCL phone's "outer" screen. With this design, a single uninterrupted screen does it all.

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As with other foldable phones, the act of folding feels physical and visceral in a way that makes me appreciate the engineering feat of any company attempting to make devices whose screens bend in half.

Foldable phones are the next frontier in phone design, delivering at least double the screen space in a package that's practical enough to tote around. Unfolded, the large screens promise an expansive display for reading, watching videos, gaming and multitasking. Folded up, you can use them on the go. Despite very real fears over screen damage that could send lofty foldable ambitions crashing to the ground, device-makers are scrambling to push out their own new designs -- to bag reputation points as much as to capture buyers' attention.

It's into this mix that TCL is dropping its wild new prototype. Best known for making really good, affordable TVs, TCL is now aligning its phone business under the same brand. The company has already trotted out concept designs and announced its DragonHinge months before this particular dual-hinge effort.

TCL's daring trifold prototype is just the start



TCL's prototype design doesn't have a name, a price or a target window for production. It doesn't even have a working screen. All that will come. For now, I'm mesmerized as I work the hinges with my hands, and imagine what it'd be like to use a triply folding device.

Folding one panel under, for example, could turn a portion of the screen into a digital keyboard while you use another part as the display. When you fully close the phone, you'd be able to use it as a really chunky handset.

Yes, you'll see creases when it's open -- and no, we still don't have bendable glass to better protect the display. That raises questions about the wear and tear on a device with a plastic cover material that's exposed to sharp objects, damage from pressure and the elements, like rain and dust. These are the same issues that plagued the $1,980 Galaxy Fold and spurred Samsung to retrofit its foldable phone to make it sturdier than its first attempt.

Tyler Lizenby/CNET

For now, there's no consensus on what the "best" foldable phone design is, and that's what makes this all so exciting. We're in the Wild West phase where any prototype or concept goes, from the vertically folding Motorola Razr that CNET discovered will come out by the end of 2019, to the square foldable phone that Samsung's rumored to be building.

Microsoft, too, has its bookish Surface Pro Duo slated for 2020 and Chinese brand Xiaomi wowed us with an early concept that has you folding back two side display panels behind a center panel.

When and if it becomes a real product, TCL's prototype will face distinct challenges with ensuring sturdy construction, a semiaffordable price and a sales plan to put the biggest foldable phone we've seen yet in front of real buyers. But enough reality for now. I let the teeming questions slide from my mind and give the Butterfly Hinge one more fold.

TCL trifold phone specs we know so far

Roughly 10-inch screen when fully opened

Four rear cameras

Front-facing camera

USB-C charger port

Iridescent finish

No headphone jack

Originally published earlier this week.