Ergonomic Vertical Design Made For Left-Handers - Our Left-Handed vertical ergonomic design helps you achieve a more natural grip, better support, and natural wrist position. With our sleek design and added support, the Adesso Vertical Ergonomic iMouse E7 is perfect for long hours of use.Adjustable 4 Level DPI Switch (800 / 1200 / 1600 / 2400) - Attain higher precision and better accuracy with your choice of 4 DPI levels. From 800 ,1200 1600 and 2400 the easily-accessible DPI button lets you quickly switch between the various computer tasks you partake throughout the day.Enhanced Optical Sensor - Optical sensor technology improves precision and even lets you work on most glass,wood,marble and leather surfaces without a need of mouse pad.Back & Forward Buttons For Convenience - Two Internet navigational buttons, back and forward, are conveniently located on the left side of mouse to provide you with Internet browser control with minimal hand movement.