Marble Mouse combines the precision of Marble technology, the fit you love and the convenience of a trackball. This innovative mouse provides comfortable curves while letting you navigate by simply rotating the trackball instead of moving the mouse on your desk.??Marble technology provides high precision with low maintenance. It replaces the mechanical parts of traditional trackballs with an optical tracking system to provide superior accuracy, reduced wear, and smooth motion, even if the ball gets dirty or scratched. And, Marble doesn't have to be regularly cleaned like the trackball. Marble Mouse fits your hand like your favorite mouse. You get comfortable and easy control of the buttons and ball whether you use it with your left or right hand.