OnePlus announced a new concept phone,????? ?????? ?????? somewhat unimaginatively called the OnePlus 8T Concept.

But the device has a feature we haven't seen on a smartphone before: It changes color.

More precisely, the back of the phone has a pattern that changes from blue to silver and vice versa. OnePlus calls the technology Electronic Color, Material and Finish (ECMF), and it consists of a special coating that contains "metal oxide in glass," which changes colors when different voltages are applied to it.

The cool part of ECMF is that, when combined with mmWave technology (the same tech used in 5G networks), it can be tied to various functions of the phone. For example, the color could change when you have an incoming call or message. OnePlus has some sci-fi ideas on how else the tech could be used — such as replicating your breathing — but even the incoming call thing sounds plenty useful to me.

There are no other details about the phone's specs; presumably, it's just a regular OnePlus 8T with a color-changing back.

The concept device, which was created by OnePlus' special design team OnePlus Gaudi, probably won't be available in stores soon — or ever. But we might see the color-changing technology applied to another OnePlus phone in the future.

The OnePlus 8T Concept is the second concept phone from the company. In January, OnePlus introduced the Concept One with an electrochromic glass panel on the back that could effectively hide the rear cameras by turning opaque when the phone is not in camera mode.