Ergonomist-approved design for all-day comfort featuring a natural handshake position to improve wrist and forearm alignment. Flexible wireless connection options let you connect to up to 3 different devices. Unique, easy-to-clean design features a built-in trackball ejection button to effortlessly remove the trackball to clean dirt, grime, and germs. Easy to use, with the same left click, right click, and scroll wheel operation as a traditional mouse. USB connectivity. Uses 2 "AA" batteries (included). Black.