... and cervical spine caused discomfort. Usage:A: hold in hand, thumb on the ball naturally, the index finger ... and right mouse button with the ordinary.a, grip in hand, thumb scroll ball b, sitting on the use, ... -bump on the application easy * Can be used in hand, no graphic support, easy to adjust the sitting ... to use on how to use* Fully ergonomic design in hand, as holding gold eggs, ease and comfort* ...