Sigma USB Dock Refurbished Micro Tune, Customize, and Update Your Lens Categories: Lens Update Lens Firmware Customize: Autofocus, OS, Focus Compatible with Global Vision Lenses # 878 MSRP: $79.00 Price: $49.00* MSRP: $79.00 Buy Now Price: $49.00* Choose mountSigma *Authorized dealer prices may vary TabsOverview 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 (4 options for focal length) x (4 options for shooting distance). Sports Line:AF Speed: 3 adjustment modes.Focus Limiter: Customize auto focus range.OS: 3 adjustment modes.