Basically that 'puck' on the top allows for '6 degrees of freedom' motion. It can pretty much move in every axis you would want to move an item in a virtual 3D environment, so you have your normal forward/back, left/right movements but it can also do up/down, twist/rotate and tilt left/right/forward/back and all the bits inbetween because it's completely fluid.What the hell is a 3D mouse? This thing looks like it came out of the dashboard of a BMW.