Kensington 64327 orbit optical trackball, black/silver the hand-hugging design of this trackball provides the comfort and support of a mouse with the ease of use of a fingertip-controlled optical trackball. Compared to a conventional mouse, the stationary orbit optical trackball requires less arm movement and saves desk space. The precise tracking mechanism is resistant to dust, reducing the need for regular trackball cleaning. Trackball includes a 6′ cord and is compatible with windows 95 or later. Usb and ps2 connectivity offers greater compatibility.