The mouse stays in one location with grippy feet and the trackball moves the cursor. There is no sensor for mouse movement. It does take a while to get used to.
The reason I chose it was that I didn't have enough desk space to move a mouse. I barely even had enough space to put the mouse. Now that I've moved house, I just like the novelty. It's not as accurate as a regular mouse.
I would love a mouse that could do both regular movement and trackball movement so I could have 4 axis inputs. Sadly, I haven't found any like that.
