The PROFI Dynamic XL construction set will allow you to learn a great deal about how balls can be moved upward in different ways. There are different methods for overcoming the force of gravity, from chain conveyors to wheel conveyors and spring launchers. Naturally with Dynamic XL we don't loose out on the fun going down either. The balls race downward on flex-rails through various obstacles and obstructions such as a stopping point, a cross-over or jump. The balls are continuously transported back up by elevators.