Haba Kullerbu Spiral Ball Track SetThis adaptable and expandable ball track is a great introduction to the Kullerbu Play World with crazy curves for Paul the ball to speed around and entertaining special effects. Insert, click, done assembling a play world could hardly be easier. Nothing can easily shake the Kullerb tracks even when the overly eager little master track builder accidentally bumps into them. The ramps, straight tracks, and curves have a hole on their lower side, into