Adesso iMouse E2 - Vertical Ergonomic Laser Mouse Ergonomic Vertical Design The vertical design provides better support for your forearm minimizing wrist pain that can come from twisting. DPI Switch Button Quickly and easily adjust DPI resolution for a faster response with the convenient DPI Switch located right beside your thumb. Battery-Saving Use the battery-saving on/off power switch on mouse base to extend battery life and reduce the need to change batteries. Advanced Laser Sensor Advanced Laser Sensor allows greater precision in mouse navigation, increases battery life, and works on more surfaces (such as glassy surfaces) than an optical mouse.