This high-performance trackball optical mouse offers a contoured shape and ambidextrous design for improved comfort for either hand during long periods of use. Smooth fingertip control: just a slight touch on the trackball lets you control the cursor with superior speed and accuracy. Patented MarbleÂ® optical technology offers enhanced precision, ensuring faster response and smooth, reliable tracking. The larger size of the trackball improves control while reducing hand and wrist motion. Four customizable buttons for easy access to key tasks.