This document discusses Testinium's extended mobile test grid solution for testing applications across multiple mobile environments and devices. The solution builds on Selenium grid to distribute tests across over 200 real mobile devices running various operating system and browser combinations. It addresses challenges like synchronizing tests executed in parallel across different devices and platforms. It leverages components like a restful synchronization service and utilities for taking screenshots and videos during test execution. The architecture uses page object models and defines test steps and flows based on device roles and layout.