Sigma USB Dock For Canon Style name:Canon Lenses   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, calibrate the lens and other customizations such as the focus parameter. For the Sports category, changes can be made to: Autofocus speed, focus limiters, manual focus override and optical stabilization functionality. Updating the firmware can be done via the internet. Sigma Photo Pro is available for Mac and PC computers.