The patented shape supports your hand in an upright neutral posture that generally avoids forearm twisting. Many users, including medical doctors, agronomists and physical therapists, said the Evoluent VerticalMouse provides superior comfort and even relieved their wrist pain.The shape is thoughtfully sculpted for uncompromised comfort and easy-to-reach programmable buttons. No finger contortions are needed to operate the buttons. The thumb rest has been reshaped to provide even more comfort over earlier versions. A bottom thumb button provides greatly extended functionality when used with the included driver. An extra wide lip along the bottom edge prevents the last finger from rubbing the desk.Pointer speed controls on the side allow convenient adjustment without even releasing your grip from the mouse. Top mounted LEDs show through the chrome thumb rest to indicate selected pointer speed including extra low (XL), low (LO), MD (medium), to high (HI). The logo is pure eye candy. The illumination turns off when the system is in sleep mode to conserve notebook battery power.