Although the result of this project should be a smartphone, the device spotted on GFXBench uses a 13.8-inch display and Android Marshmallow, but also a Snapdragon 810 processor and 3 GB RAM, so it might be a large screen tablet after all.
http://www.notebookcheck.net/Google-Project-Ara-modular-device-hits-GFXBench.158877.0.html