Trackball Assembly - 3" with USB & PS/2 Interface - 56-0300: Please choose your color. 3" solid Trackball assembly w/ USB & PS/2 Interface. No interface needed to connect the Suzo-Happ trackball to a PC. Connects directly to either a PS/2 (mouse) port or a USB port on a PC through the included 6-foot cable . Automatically detects whether it is connected to a PS/2 or a USB port and configures itself accordingly . Compatible with Windows 98 or higher and Mac OS 8.5 or higher, Linux with USB HID support. No external power supply needed. Supports up to three buttons. (Three-button functionality will require the use of a driver that supports three buttons. The standard MS driver supports only two, and the MAC OS supports only one). A wire harness is included which will connect to the Suzo-Happ Horizontal, Ultimate, Competition or Illuminated pushbuttons. Includes both .187" and 250" terminal connectors for pushbuttons. Durable black polycarbonate plastic material. Exceptional performance and precision is achieved from harden steel shafts. Pushbuttons and mounting plate kits are sold separately. Part Number: 56-0300