The Phantom Ultimate, Tecno’s idea rollable phone, was unveiled last year. Though it was merely an idea that could be seen in demo films, the company now has some working prototypes that it presented to the MWC. had a chance to test out the Ultimate and a few other intriguing concepts that are being developed at Tecno HQ.

Even though it might never be sold in stores, the Phantom Ultimate is currently a functional device. The phone’s 6.55-inch display, which encircles the left edge, is where it starts. It expands when a button is pressed, and in only 1.3 seconds, the diagonal extends to 7.11″ (with a different aspect ratio, of course) as more screen spools out.

Put that in quotations because the “second display” that is rolled around the rear is actually the main and only display. This display is viewed through a glass pane, so there’s no need to be concerned about breaking it. It’s a resourceful use of existing infrastructure.

Android has been forced to improve its support for screens that abruptly change in size and aspect ratio due to the popularity of foldable phones. This is also well illustrated by the Tecno Phantom Ultimate, whose apps and user interface change in response to screen size adjustments.

The device’s thickness, 9.93mm, was previously the thinnest of any foldable, but some horizontal folding devices have since dropped below the 10mm threshold.

Tecno now has two folding phones on the market: the Phantom V Fold and the V Flip, but the company is still in the early stages of testing rollable phones. The engineers at the company have been quite busy thinking of ways to improve them.

Their creation, the Borderless Foldable Main Screen, is one example. Its name speaks for itself: the manufacturer was able to improve the screen-to-body ratio of the phone by reducing the bezel surrounding the screen by altering the way the Ultra Thin Glass (UTG) is fastened to the phone.

The Chameleon Color Technology, which is essentially a rear panel that can be adjusted to one of several thousand hues, was introduced by Tecno at last year’s MWC. Sub-micron prisms that are rotatable by a magnetic field are used to accomplish this.

This indicates that the effect requires ambient light to function, but it also requires extremely little power—milliamps or less—to work. Additionally, it moves quickly—it takes only 0.03 seconds to change colors. Furthermore, according to Tecno, this has an extremely long service life, so you shouldn’t be concerned about it breaking down.