The Sigma USB dock works in conjunction with Sigma Optimization Pro software in order to connect a photographers lens to their personal computer to update firmware and other parameters such as focus, and for the Sports category: Autofocus speeds, focus limiters, and optical stabilization functionality. Updating the firmware can be done via the internet. Sigma Photo Pro is available for Mac and PC computers.Focus Settings:- 4 Categories of customization for fixed focal length;- 16 Categories of customization for zoom lenses.