The Sigma USB dock enables you to update the lens firmware an adjust parameters like focus on your Sony lens when you connect it with your computer. It has the SIGMA Optimization Pro, a special software that helps you configure focus settings and the firmware easily. It also enables you to customize sports line specific lens with three different AF speed mode to modify the lens' autofocus. It also gives you the option to constrain focus distance within a specific range to suit your personal shooting habits.