The arow in circle will always pont to your mouse. If you spin it around the circle clockwise, and keep it on the left half of the circle the whirlblock will whirl clock wise. If you spin it around the circle anti-clockwise and keep it on the right side of the circle, the whirlblock will whirl anti-clockwise. When the arrow crosses the red line the whirlblock starts whirling the other way.
