WeatherTRAK WTPRO-6STA-KEY ET OptiFlow XR® 6 Station Key for Pro3. WeatherTRAK OptiFlow XR® is an advanced flow management controller available in conventional wire or 2-Wire configurations. OptiFlow XR leverages its visual and easy-to-use interface making it easy to manage complex flow across entire sites. By enabling controllers to share information in the cloud, OptiFlow XR optimizes how, when and where watering takes place within your water windows.