Add comfort and control to your computing experience with the Trackman Marble Mouse from Logitech®. This mouse keeps you comfortable and supported all day – and stays in one place .A trackball design with a long, broad palm area and gentle curves keeps your hand comfortable and supported all day – whether you use your right or left hand. The Button controls let you easily move forward and backward when you’re surfing the Web. The Optical technology gives you smooth tracking on almost any surface so you can be productive wherever you work.
http://www.logitech.com/en-us/product/trackman-marble