Gravitrax Action Set - TwistGRAVITRAX Construction Set ACTION SET TWIST. The set includes everything you need to build individual marble runs. Unlimited fun thanks to endless possibilities. With the GraviTrax Action Set Twist you can create different and individual runs. The included action elements allow for endless fun? The spiral allows the balls to quickly overcome differences in height, can be assembled individually and therefore fits perfectly on any run. The trampoline