Pi-Top's modular rail system that comes with the new notebook case allows users to add more optional modules. In addition to the new 14-inch 1080o display with the case, Pi-Top also included a Videocore IV 3D GPU, an hdmi port and an 8 GB microSD card preinstalled with the Android-based Polaris OS.
https://www.notebookcheck.net/Pi-Top-adds-14-inch-screen-upgrade-to-its-modular-Raspberry-Pi-notebook.258348.0.html