The bluefin itself. It is a hand-held 'box' that plugs into the OBD2 port (like a diagnostic device) and all you do is follow the directions on the display. It then plugs into your USB port on your PC to access the Superchips server. All you do is follow the bouncing ball in all instances! The bluefin also has limited diagnostic capability. I already have DIS etc so I haven't tried that function.