This innovative trackball combines advanced cordless and optical technologies with useful new buttons: advanced scrolling buttons, scroll wheel, drag lock button, forward and back buttons. This cordless, finger-operated trackball eliminates the cord clutter and provides precise, accurate, optical performance. Logitech's advanced digital radio technology combined with Marble Optical performance is reliable and responsive. Logitech's smart power management allows the trackball to work beyond six months on the included AA batteries. The low battery indicator gives plenty of warning before the batteries need to be changed. The ultimate trackball. Only from Logitech.