With The Gravitrax Interactive Track System; You Can Design And Build Your Own Marble Runs And Experiment With Gravity; Magnetism; And Kinetics To Propel Your Marble To The Finish. With A Variety Of Tiles; Levels; Tracks And Elements; You Can Control The Speed Of The Marble. The Open-Play Concept Offers Endless Possibilities To Design A Different Track Every Time You Play. Add Flair And Speed To Your Tracks With Expansion Sets And Action Accessories. Experience The Power Of Gravity With This Epic Marble Run Toy.The Zipline Connects Track Sections To Overcome Long Distances And Varying Elevations. Combine The Zipline With The Gravitrax Starter Set For Spectacular Gliding Action. How Far Will Your Marbles Go When Connected Across The Tracks Via Zipline?This Open-Ended; Screen-Free Stem Toy Makes The Perfect Activity For Boys And Girls Ages 8 And Up.