If you're old enough, you will remember the wind up Evel Kinevel (sp!). You roud up a handle, pressed a button and Evel would shoot across the room and smash into the skirting board, just like the real thing. Rollers (until you get used to them) are like a full size version of 'wind up Evel'. Turbos are much easier but rollers give a much more realistic 'feel'.