TRACKBALL COMFORT - Equipped with a 44mm trackball, you will not need to mouse around to move the cursor as thumb controlled trackball stays in one place. Not only work on flat surfaces, but also on your leg, sofa and other surfaces as well. A full control of everything is within your fingers. | ERGONOMIC DESIGN - Places your hand in a natural wrist & arm position for smoother movement and less muscle tension. Comfortable finger rests just fit in the palm of your hand. No driver required. Once you get used to it, you will love it! | 4 ADJUSTABLE DPI LEVELS - The SANWA trackball provides precise cursor movement for superior accuracy so you can get where you want on the screen quickly with less hand movement, improving productivity and efficiency. You can adjust the mouse among 4 resolutions of 600 / 800 / 1200 / 1600 DPI depending on your needs. When the count switch button is pressed, the DPI is notified by the number of flashes. | PROGRAMMABLE BUTTONS - This SANWA ergonomic trackball mouse also has a forward/back function. Besides, it is programmable for different functions. Download SANWA Trackball mouse software to customize your mouse buttons and increase work efficiency. Note: 1. The software does not work with Mac OS or Chrome OS. 2. Programmable function works when the software on. | NOISELESS BUTTON - The noiseless button is mounted on the left and right clicks. Suitable for late-night PC operation, operation in quiet places such as public places, library, hospital or meetings.