... Ergonomic design, anti-strain-injury Vertical upright erect Optical MouseFeature:Vertical design,3 button optical mouse. Patented sharp, comfortable to use.Ergonomic ... , anti-strain-injury.Suitable handle, more steady of keystrokes.Latest optical orientation technology adopted.SpecificationWeight150gDimension235x225x85mmResolutionUp than 800dpiSystem requirementWindows 98/2000/ME ...