Telephone manufacturer Essential is working on a new narrow smartphone under the name Project GEM, the company announced on Wednesday via Twitter.

In addition, a video by Essential founder Andy Rubin shows that the color of the back changes based on the viewing angle.

Essential has not disclosed more information about the new smartphone. Based on the image, the device appears to be equipped with a camera lens and a fingerprint scanner on the back.

The new smartphone is currently being tested by Essential employees. When the company expects to launch the product is unclear. The Essential Phone, the first and as yet the only phone in the company, is no longer produced.