Perixx PERIMICE-713 Wireless Ergonomic Vertical Mouse - 1000/1500/2000 DPI - Right Handed - Recommended with RSI User Wireless 2.4G Technology with 30 Ft Operating Range 1000/1500/2000 dpi Optical Resolution with DPI Switch High Quality Rubber Coating Surface With this version, the scrolling wheel has been updated with the new parts. The scrolling problem has been solved and controlled with this version. On/Off Switch - 2xAAA Batteries Required (Not Included in the package)