Microsoft SideWinder X3 Mouse 2000 DPI Laser Tracking Engine2000 DPI Laser Tracking Engine - For fast action Built to Last - Main button life: Rated to 10,000,000 clicks Either-Hand Comfort - Familiar shape for right- or left-handed comfort that fi ts most hand sizes Weight-Balanced Plus Wide Glide Feet - Smooth handling and active feel Low-Profi le Lateral Side Buttons - Easy access during gaming and everyday computing