Parts: Remarks for Windows based PC/laptops: 1. Before you connect two or three monitors, we suggest you lower monitor resolution, please check Q3 in Quick Start Guide for details. 2. Before you connect three monitors, we suggest you disconnect laptop/PC first, please check Q2 in Quick Start Guide for details. Remarks for Mac based PC/laptops: 1. When you connect only one external monitor to the dock, the extend and duplicate modes are both available. 2. If you have two or three monitors connected to the dock, then you can only extend to one monitor while the other one or two monitor(s) will copy the same content on your extended monitor.